While Hyouki covers a lot of the fundamentals of teambuilding, this is an extension to that guide mainly because I don't want to mess with his content too much and because I'm lazy, and a hypocrite for writing something this long. That said and done, let's get started.

The Team

"There is no 'I' in 'team'". That's certainly true, and to be quite frank, captain obvious. Nevertheless, still true. However, "me" can be spelled out using the letters given. A team should consist of six Pokemon that can work towards a common goal together. It's like Communism, but not that it affects your life in any way. Each Pokemon should be able to some how contribute to the team, and be able to pull their weight, while not hampering each other in the process, all working towards the common good. This leads into synergy, or in other words, how well things work together. The most basic kind of synergy is defensive type synergy, which is pretty much a combination of 2 or more Pokemon that can cover each other's weaknesses well. In this case, I'll use a Rotom-W, Gliscor, and Jirachi combination:

Rotom + Gliscor + Jirachi

Rotom-W is weak to Grass-type moves, which Jirachi resists. Jirachi's Ground and Fire weaknesses are covered by Gliscor and Rotom-W respectively, though Rotom-W can cover both because it has Levitate as an ability. Gliscor's Ice and Water-type weaknesses are nicely covered by Jirachi and Rotom-W respectively. Many Jirachis that are used in tangent with this combination also run a hefty amount of Special Defense EV investment to boost its already great Special Defense. Gliscor's naturally good Defense stat allows it to take on many physical hits. Rotom-W has good all-around bulk, sporting solid 107 defenses on both sides of the spectrum. This core itself is able to achieve multiple things in a short amount of Pokemon: excellent typing synergy and general defensive synergy, sporting a dedicated special, physical, and mixed wall. It also underlines the importance of efficiency when choosing Pokemon for a team: get as little Pokemon as possible to fulfill as much jobs as possible. But not too much, or that just falls apart because individual Pokemon are given too much pressure. It's a really cool core that I eventually bugged Lohrak enough about that he started using it.

When you start teambuilding, you should at least have a vague idea of how you want your team to function, be it overrunning your opponent with high-powered attacks or playing on the defensive and outlasting your opponent. Or maybe even both. In this article I will be mainly focusing on balanced teams, a format that can go either way.

Selecting the Members

When you select your members, it's like selecting members for an elite mission, that being to demolish your opponent. You want the right people for the mission, be able to respond to any situation, and never back down.

A team is somewhat like that. Your mission, while demolishing your opponent, also comes with the question of "how". How are you going to do it? This should be the central theme of your team, as mentioned earlier. For a balanced team like this one, both offensive and defensive Pokemon need to be present to be able to get a job done well. Unlike Hyouki and his ugly Tyranitar, this team will be focused on Rain and its elegant Politoed.
Politoed
Just look at how cute he is!

The basic team structure that I'm building this team around can be broken down into parts: 1-2, 3-5, and 6, all of them representing Pokemon on the team. While this is a 4th gen format for teambuilding, it is still applicable to many teams to this day.

Pokemon 1 and 2

Pokemon 1 and 2 are your lead and lead support Pokemon. While thanks to Team Preview taking out the effectiveness of dedicated leads, because this is a weather team, Politoed is the lead for the most of my battles. Pokemon 2 is the lead support. The lead support is also capable of leading, but more importantly, it is able to help the lead combat any problems that it may face. Likewise, the lead itself helps the lead support, generating an internal synergy within multiple parts of the team. This is good, as it gives you many options to fall back on. My lead support in this case is Latios. Latios is able to synergize with Politoed pretty well. It can take on Grass and Electric moves that are fired at Politoed, while Politoed, though not covering Latios as well, can take an Ice Beam for him. Latios also plays an important role in combating sun, the arch enemy weather of Rain. Against a sun team it is important to use Latios well and wisely. Last but not least, Latios can benefit from a powerful Rain-boosted Surf that alone can kill quite a few things.
Politoed
Politoed @ Leftovers
248 HP / 252 Def / 8 Spe
Bold
- Scald
- Perish Song
- Toxic / Ice Beam
- Encore / Protect

Politoed is an important member to this team, summoning rain without even needing to dance. The natives of agricultural societies will want one ASAP.

EVs / Nature: Quite obviously it lets Politoed get a huge physically defensive bulk. The HP is a bit weird, at 248 instead of the optimal 252. Why? 248 gives Politoed an HP amount that is indivisible by 8, meaning that it can switch into Stealth Rocks a larger number of times without dying, improving longevity and usefulness in the weather war. A bit of Speed investment to outpace other Politoeds.

Moveset:
Scald - Scald is useful both as a STAB move, and as a device for silently sabotaging members of the opposing team with a potential burn.

Perish Song - This enables Politoed to stop Baton Pass chains that would other wise be deadly if they set up, and also helps stop boosting sweepers when used in conjunction with Encore. Politoed, though generally considered a bad Pokemon by many players, is useful in forcing mid-late game switches that can turn the battle into your favor.

Toxic - An option that will hit Gastrodon and Jellicent, both of which cause this team some problems. While some may suggest Hidden Power Grass as an alternative, in addition to extra coverage, Hidden Power Grass lacks the ability to 4HKO Physically Defensive Jellicent with Leftovers and can't 2HKO Max Specially Defensive Gastrodon, allowing for both of them to just use Recover to heal off the damage. Ice Beam is preferable if you want to kill Dragons more easily, but meh.

Encore - The last move depends on your personal preference. Politoed is a somewhat versatile Pokemon. Encore lets you catch boosting sweepers and can work well in conjunction with Perish Song, while Protect can quickly wear down opponents thanks to the Scald burn or the Toxic poison. It really boils down to preferences.

Latios
Latios @ Life Orb
4 HP / 252 SAtk / 252 Spe
Timid
- Draco Meteor
- Surf
- Psyshock
- Roost

While Politoed runs a Defense oriented set, Latios has solid Special Defense. Look! Another internal synergy! Latios is fully capable of abusing rain with powerful surfs, and even defending it from its arch nemesis Sun. Latios is also a swift and fast killing machine with as well with its great 110 Base Speed.

EVs / Nature: This Latios set is fairly straight forward, in particular the EV Spread for maximum speed and killing power, while the nature offers optimal speed.

Moveset:
Draco Meteor - While Draco Meteor seems unfavorable in its Special Attack drop, it allows Latios to essentially get a free kill, even more so in mid-game when the opponent's team is pretty weakened. At that point it's more or less just get Latios in, Draco, switch out, rinse and repeat. The excellent synergy with the rest of the team enables this to happen very often and it is easy to get this mighty dragon into play, more discussed in later sections of this article. Oh, and did I mention that it looks really cool?

Surf - I want to abuse rain. Rain boosted surf from Latios is pretty powerful, being able to do over 40% to Specially Defensive Jirachi, one of its best counters. This means that Jirachi needs to stay >80% health at all times if it wants to switch into Latios and not get 2HKOd by it. Surf also does some 70%+ to the typical CB Scizor that runs 248 HP investment, and a solid 2HKO on Specially Defensive Scizors that have 252 HP / 216 SDef and a Positive nature for Special Defense. However, Tyranitar and Ferrothorn are still large problems, as well as a slew of lesser used Pokemon. Because this set lacks Hidden Power Fire that most Latios sets run, or for a spin, Hidden Power Fighting because they hit the same targets - steel types, for the equal amount of damage under rain, with Fighting having the added bonus of being able to follow up a kill on Tyranitar after using Surf on it, Tyranitar and Ferrothorn present themselves as big problems for Latios, and Ferrothorn a pretty big one for the rest of the team. However, I like neither because of the Speed drop in the IVs that is required to use them.

Psyshock - There are certainly other options that can go here, but Psyshock is useful for nailing things like Blissey on the switch and getting a 2HKO if Stealth Rocks are up. It also enables Latios to hit a lot of Special Walls that it couldn't hit as hard before. Psychic is not an excellent offensive typing in itself, and is generally a bit underwhelming in my opinion, but it nevertheless still gains STAB in the case of Latios.

Roost - Many players go to Recover by default, but due to the nature of how Roost works, Pokemon with Levitate do not suffer the temporary typing loss that comes with roost. So from time to time you Roost while someone Earthquakes and they're like wtf. Roost is useful in keeping Latios healthy throughout the battle. Endurance and stability are important in Balance - Defensive oriented teams. You want your Pokemon to last as long as possible yet dealing high damage. I believe Latios fits this role very well.

Pokemon 3-5

Pokemon 3-5 are generally your team's core. The defensive core has good synergy between themselves, can continuously switch and absorb hits from all sides of the spectrum. I'll use the Rotom-W Gliscor Jirachi core I discussed earlier. It is absolutely mandatory that you try to keep this core alive for as long as possible for maximum effectiveness.

Another element that this core introduces is "Volt Turn". The basic concept of Volt Turn is to use to two moves Volt Switch and U-turn to consistently get a favorable matchup against your opponent. For example, say your opponent switches in Latias on Rotom-W while Rotom-W Volt Switches, Rotom-W can then go into Jirachi or Scizor, both of whom can counter Latias, and U-turn themselves, gaining momentum while Latias is threatened out, and rinse and repeat.
Rotom
Rotom-W @ Choice Scarf
4 Def / 252 SAtk / 252 Spe
Timid
- Hydropump
- Volt Switch
- Hidden Power [Ice] / [Grass] / Thunder
- Trick

Rotom-W is the first member of the Rotom-W Gliscor Jirachi core, and can also be arguably considered Pokemon #2 because it is the Pokemon on this team that most benefits from Rain outside of Toxicroak, who perhaps receives a better boost. Rotom-W acts as a speedy revenge killer, hitting 447 Speed with a Choice Scarf, while maintaining good momentum with Volt Switch, or firing off powerful Hydropumps. Trick is another tool at Rotom-W's disposal, enabling him to screw around with the opponent's team's items, and is very useful for crippling one member of an opponent's stall team, usually Blissey or Ferrothorn.

EVs / Nature: The EVs are rather self-explanatory in giving Rotom-W maximum offensive potential. The remainder 4 EVs that is traditionally put into HP is instead invested into Defense because it helps balance out Rotom-W's defenses, which is beneficial in being able to screw around the Download ability, which will increase Special Attack if both of the opponent's defenses are equal - Genesect can no longer hit Rotom-W with as powerful a U-turn as before because only its Special Attack is raised, and if it is faster and uses Bug Buzz, I can easily go into Gliscor, Scizor, or Toxicroak and set up on it or just hit it hard.

Moveset:
Hydropump - Under rain, Hydropump hits super hard, reaching near the same damage as Latios's Draco Meteor. That's pretty powerful stuff. Hydropump also allows Rotom-W to potentially 2HKO all variants of Jirachi as long as it doesn't miss.

Volt Switch - Rotom-W has a fantastic ability to Volt Switch to net momentum. Together with Scizor and Gliscor, it has perfect type synergy, and can put the opponent under a lot of heavy pressure. Volt Switch should usually be your primary move of choice when playing Rotom-W early game. Only when your opponent's team is largely weakened should you try to use Hydropump or any of the other moves.

Hidden Power [Grass] / [Ice] / Thunder - Hidden Power [Grass] lets you hit Gastrodon. That's pretty much all it's used for, and Gastrodon can be pretty annoying, so it's not a bad option to consider. [Ice] lets you revenge kill Dragons like Dragonite, and give you a more reliable way to beat Gliscor, as over time, Gliscor may be able to Protect-stall out your Hydropumps. Thunder is just for high-hitting damage, and can be used as a more reliable late-game sweeping material over Hydropump.

Trick - Cripples walls and messes around with your opponent. There's not too much to it, and try not to get rid of your Choice Scarf too early unless it's either absolutely necessary or Rotom-W already outspeeds every single member on the opponent's team and nothing can set up with Agility or Dragon Dance. However, Tricking a Dragonite while it Dragon Dances on Rotom-W can be very amusing.
Gliscor
Gliscor @ Toxic Orb
244 HP / 28 Def / 236 Spe
Impish
- Earthquake
- Ice Fang / Roost / Stealth Rock
- U-turn
- Taunt

Gliscor, though only lightly invested in Defense, is still a good defensive Pokemon. This Gliscor set is a bit weird, but not unuseful. Gliscor serves as a fast stall breaker, letting you Taunt when necessary, then pulling out with U-turn. Heh heh, pulling out. Ice Fang can be replaced with Stealth Rocks if you opt to have U-turn on Jirachi. As the second member of the primary core, Gliscor pivots, Taunts, and of course, U-turns for momentum.

EVs / Nature: The EVs allows Gliscor to beat all non-boosted Base 80 Speed Pokemon. That's a pretty fast role for such a defensive Pokemon. By hitting this speed mark, Gliscor can make some swift kills that the opponent may not expect. While Toxic-Stall Gliscor is rising in popularity, and runs a good amount of Speed - enough to beat Base 90 Neutral, which is slower than this Gliscor, many players still look for a more traditional, slower Gliscor, and therefore may get careless around this Gliscor in thinking that it's a lot slower than it really is.

Moveset:
Earthquake - Earthquake is pretty standard on most Gliscors and hits surprisingly hard considering that it only has 95 Base Attack and is uninvested. Don't count on it to take down Pokemon from full health though, but that's where the Scizor and Rotom-W come in, softening up Gliscor's counters and checks until Gliscor can get past them himself, or just U-turn out to weaken them more.

Ice Fang / Roost / Stealth Rock - Ice Fang's only real purpose is to do 59% to offensive Dragonite, and a bit more to non-Intimidate Salamence, and maybe go a bit head-to-head with other Gliscors, but Rotom-W's HP Ice and Latios can do that much better. Roost is an option for recovering health, while Stealth Rocks lets Gliscor be the hazard setter if Jirachi opts to not carry Stealth Rocks, and U-turn instead.

U-turn - Gliscor forces quite a bit of switches and therefore is a fantastic user of U-turn. U-turn lets Gliscor maintain momentum between a core of Scizor and Rotom-W, while hitting off for some decent damage. Because this Gliscor has so much speed, it can comfortably U-turn against nearly all Rotom-W's carrying Leftovers - which implies that they're defensive and therefore Gliscor can outspeed them and U-turn to your own Rotom-W, Latios, Breloom, or Toxicroak.

Taunt - Taunt sees use when Gliscor plays against stall. Taunt helps prevent the opponent from as easily setting up hazards, and prevents stall teams from functioning as effectively as they would otherwise. It's not used that much but is definitely helpful and can pull you out of tight spots when necessary.
Jirachi
Jirachi @ Leftovers
252 HP / 4 SAtk / 252 SDef
Sassy
- Thunder / Body Slam
- Iron Head
- Wish
- Stealth Rock / U-turn

Jirachi functions as the dedicated Special Defensive Wall on this team as well as an important member in the Rotom-W Gliscor Jirachi core. Jirachi's Steel typing has its Fire-type weakness cut in half under rain, which is a nice boon against Dragons such as Hydreigon, allowing for more easy switches without having to worry about Fire Blast or other Fire-type moves as much. Paralysis support as well as Wish support provided by Jirachi are much appreciated to slower Pokemon and Pokemon who do not have a form of recovery.

EVs / Nature: Many Specially Defensive Jirachis run a bit of Speed, but that's not necessary when everything's slower than you due to Paralysis. Maximum Special Defense makes Jirachi nearly invincible from the Special side, and lets it pivot nicely and force switches along with a fantastic array of resistances.

Moveset:
Thunder / Body Slam - Under rain, Thunder is generally preferred over Body Slam, but with the increasing popularity of Thundurus-T, Body Slam is nevertheless and option to be considered. Both have a solid 60% Paralysis rate and makes the opponent think twice before switching in anything. Thunder has an added benefit of hitting Bulk-waters harder.

Iron Head - Iron Head makes Jirachi a real dick. Alone, it has a 60% chance of flinching, and against a paralyzed opponent, 70% chance of making the opponent incapacitated that turn through either flinching or paralysis. However, this shouldn't be your main form of attack, as flinching a faster opponent on a switch is not very helpful, but Thundering and Body Slamming for the paralysis is more helpful.

Wish - At 202 HP recovery, Wish from Jirachi is welcomed by everyone. It also gives Jirachi a form of recovery himself, as well as the weather starter during a weather war. Very helpful.

Stealth Rocks / U-turn - It was hard to fit Stealth Rocks onto this team, but Jirachi, or maybe Gliscor, did it! Rocks provides the ever useful residual damage and benefits the added pressure for Volt Switch and U-turning, while U-turn lets Jirachi pass wishes himself as well as momentum. Because Jirachi is rather slow, it's almost guaranteed to move last against an unparalyzed opponent. If the opponent can't really touch Jirachi, but stays in anyways, Jirachi can simply Wish and then U-turn next turn to a new Pokemon, with the new Pokemon taking no damage from your opponent's current Pokemon while gaining 202 HP. U-turn also lets Jirachi escape Magnezones, and gives the team better defense overall against Dragon-spam teams.

Pokemon 6

Pokemon 6 is generally a filler Pokemon that can be swapped depending on rising threats in the metagame. For example, imperfectluck, a famous Shoddy Battle player, had a stall team with a solid 3 member core, 2 phazers, and a last member that changed every now and then. However, this is not to say that Pokemon 6 is useless. Pokemon 6 is also commonly the Pokemon that patches up the team's remaining weaknesses, and is equally essential in many cases in how well the team functions. This team, throughout its life span, has had three different Pokemon play Pokemon #6, each fulfilling a different role that all benefits the team as a whole.
Scizor
Scizor @ Choice Band
204 HP / 252 Atk / 52 Spe
Adamant
- U-turn
- Bullet Punch
- Superpower
- Pursuit

Scizor helps the team take an offensive stance, being able to be implemented with the team's internal theme of Volt Turning. Scizor is a classic member of this style of game play, and synergizes very well with Rotom-W and Gliscor, the key members in the Volt Turn combo on this team. Scizor speeds up the team, bringing out advantageous switches, and cleans up end game with a powerful STAB. EVs / Nature: The EVs allows Gliscor to beat all non-boosted Base 80 Speed Pokemon. That's a pretty fast role for such a defensive Pokemon. By hitting this speed mark, Gliscor can make some swift kills that the opponent may not expect. While Toxic-Stall Gliscor is rising in popularity, and runs a good amount of Speed - enough to beat Base 90 Neutral, which is slower than this Gliscor, many players still look for a more traditional, slower Gliscor, and therefore may get careless around this Gliscor in thinking that it's a lot slower than it really is.

Moveset:
Bullet Punch -

U-turn -

Superpower -

Pursuit -
Breloom
Breloom @ Toxic Orb
204 HP / 218 SDef / 86 Spe
Careful
- Bulk Up
- Seed Bomb
- Drain Punch
- Spore

Breloom is a second option for the 6th member of the team. Breloom is extremely useful for countering most sand and stall teams. Poison Heal, once activated with Toxic Orb, means that Breloom cannot receive any new Status conditions, and is therefore useful as a secondary status absorber, after Gliscor. I have no idea what the EVs accomplish, as I just copied this off of the original set and made slight adjustments to make it faster and outpace others of its kind.

Moveset:
Bulk Up: - Breloom is cool as a set up sweeper. The EV spread, despite me having little idea outside of what it does except for speed, does evidently give Breloom a good amount of special bulk. Bulk Up helps increase Breloom's physical side's strength, and can be trouble some to most stall teams as they can't hurt it with status, and Poison Heal recovers a lot of HP Back when Breloom is hit with a weak move. As such Breloom is problematic to many stall teams. Breloom is also, when used, a key player for combating rain teams and beating Ferrothorn / Jellicent cores that would otherwise give this team lots of trouble.

Seed Bomb: - Grass is a poor, though sometimes necessary, offensive typing. However, it is very useful when going up against rain teams, which has lots of Water-type Pokemon. Seed Bomb also offers a form of STAB on Breloom, and coming off of 130 Base Attack, even without investment, stings a bit.

Drain Punch: - Additional form of recovery for Breloom. Sometimes Poison Heal alone is just not enough. Drain Punch ensures that Breloom stays constantly at good health, and is always appreciated and useful for both being a decently powered Fighting STAB and a tool for taking out opposing Steel types. However, Grass / Fighting offers relatively poor coverage, though very useful when needed, against a good portion of the competitive Pokemon used. For example, Dragonite can easily set up on Breloom, using Lum Berry to shrug off the Spore, and OHKO back if Breloom doesn't already have any Bulk Ups. Breloom can't really touch Dragonite in return.

Spore: - Spore is perhaps something that makes Breloom so useful. Spore, due to the new sleep mechanics of sleep turns resetting, practically allows Breloom to completely incapacitate a Pokemon for the rest of the battle. Giving your sleeping Pokemon 2-4 turns to wake up essentially lets your opponent kill it or just set up all over it and then kill it. It's pretty useful, not to mention annoying.

Toxicroak
Toxicroak @ Life Orb
4 HP / 252 Atk / 252 Spe
Jolly
- Swords Dance
- Drain Punch / Cross Chop
- Ice Punch
- Sucker Punch

Toxicroak is a very underrated Pokemon yet very powerful. Toxicroak can essentially demolish opposing rain teams thanks to its Water resist and somewhat useful defensive typing. After a single Swords Dance, a wide load of Pokemon are OHKO'd. This essentially allows Toxicroak to counter-sweep fast paced and offensive rain teams by switching into something that's locked into a Water-type move courtesy of a choiced item, and then setting up and sweeping, picking off the faster Pokemon like Tornadus and Latios with Sucker Punch.

EVs / Nature: The EVs are fairly straightforward for a fast, offensive Pokemon. The nature was originally Adamant, but changed to Jolly to combat the rising popularity of faster Gliscors that have speed to outspeed Adamant Toxicroak, but not Jolly. The loss in power is slightly noticeable, but not too much.

Moveset:
Swords Dance: - Main set up move. Toxicroak gains an immense amount of power after just one turn of use, allowing the adamant version to OHKO Skarmories that have switched into Stealth Rock twice with Cross Chop, which is a pretty impressive feat. It also allows Toxicroak to OHKO Offensive Dragonite with Ice Punch through Multiscale, which is really something considering that Dragonite is pretty bulky after Multiscale, and moves like HP Ice often can't even kill it if its ability is nulled and it's closed to full health.

Drain Punch / Cross Chop: - Toxicroak's primary Fighting-type STAB. Drain Punch gives Toxicroak continuous healing, and is pretty useful if Toxicroak is coming in a lot and getting damaged, despite the fact that Dry Skin already offers it a huge amount of HP per turn. Cross Chop is a bit more powerful, but misses when you most need it. The power difference between the two, however, is very noticeable, and it goes either way depending on what you like better.

Ice Punch: - Cool coverage move. Literally. It helps nail a lot of Pokemon that Bulk Up-Substitute Toxicroak can't nail, mostly Dragons coming in, Gliscor, and on the occasion, Landorus / Landorus-T.

Sucker Punch: - Gives the team a form of priority, which is nifty. It can nail faster Pokemon such as Latios, and Tornadus after Stealth Rock, as well as Volcaronas that can be annoying. Sucker Punch and Drain Punch / Sucker Punch also offers near-perfect typing coverage, hitting everything bar a few Pokemon for at least neutral damage, which is fixed by Ice Punch.

Threats

Tyranitar
Celebi
Ferrothorn
Jirachi