Shauntal

Type: Ghost
Preferred Pokemon: Liepard, Bisharp
Prize: $6000

Cofagrigus @ Level 48 Ability: Mummy - Shadow Ball - Will-o-Wisp - Grass Knot - Psychic

Jellicent @ Level 48 Ability: Cursed Body - Shadow Ball - Energy Ball - Surf - Brine

Golurk @ Level 48 Ability: Iron Fist - Brick Break - Earthquake - Shadow Punch - Curse

Chandelure @ Level 50 Ability: Flame Body - Fire Blast - Psychic - Shadow Ball - Payback

Shauntal may look hard on paper, but here team is really easy to defeat with a really good Dark-type. Unfortunately, Liepard isn't what I would consider 'good' but it works will considering her Pokemon's lack of speed. Chandelure's speed is the highest of this quartet, and is also the one you should be the most worried about. Liepard will outspeed Chandelure, and hit hard with Night Slash. Night Slash will take out Golurk completely, as well as Cofagrigus (Low HP + Super Effective = BOOM). Jellicent may be a problem since it's bulky, but Bisharp can handle it with Night Slash. I don't recommend Bisharp only because of Chandelure and the trouble it will face with Marshal and Grimsley. (Then again, Liepard won't stand much of a chance either! )

Grimsley

Type: Dark
Preferred Pokemon: Galvantula, Sawk/Throh
Prize: $6000

Scrafty @ Level 48 - Sand-Attack - Crunch - Brick Break - Poison Jab

Krookodile @ Level 48 - Earthquake - Crunch - Dragon Claw - Foul Play

Liepard (F) @ Level 48 - Night Slash - Attract - Fake Out - Aerial Ace

Bisharp @ Level 50 - X-Scissor - Night Slash - Metal Claw - Aerial Ace

So Grimsley is a weird guy. xD His team is pretty easy to defeat with Galvantula. Spam Bug Buzz on all of his Pokemon, considering you outrun them all. You might want to go with Thunder for Bisharp, just to do a bit more damage (and Bug Buzz no longer is super-effective on Bisharp). Scrafty's bulky, but won't last long with STAB'd Bug Buzz.

Marshal

Type: Fighting
Preferred Pokemon: Jellicent, Musharna
Prize: $6000

Throh @ Level 48 - Stone Edge - Storm Throw - Bulldoze - Payback

Sawk @ Level 48 - Stone Edge - Retaliate - Karate Chop - Grass Knot

Conkeldurr @ Level 48 - Stone Edge - Hammer Arm - Grass Knot - Retaliate

Mienshao @ Level 50 - U-Turn - Jump Kick - Rock Slide - Retaliate

So Marshall just may be the hardest on in the entire group. His Pokemon are ready for nearly all types, and struggle only with the likes of Jellicent and Musharna. Jellicent is a great candidate because of bulk and its ability to spread burns with Will-O-Wisp. Burns reduce Attack, which makes defeating Marshall's Attack-centric team so much easier. If you're looking for a more exciting approach, use Scald and burn his team with boiling water. :p And fear not for Jellicent. Conkeldurr and Sawk's Grass Knot will do minimal damage due to their horrible Special Attack.

Musharna also works because of it's Psychic-typing. The only real problem is Mienshao, since it knows U-Turn, but Musharna is bulky enough to absorb the blow and strike again with a STAB'd Psychic.

Caitlin

Type: Psychic
Preferred Pokemon: Galvantula, Bisharp
Prize: $6000

Reuniclus @ Level 48 - Energy Ball - Psychic - Focus Blast - Thunder

Musharna @ Level 48 - Reflect - Thunder Wave - Shadow Ball - Psychic

Sigilyph @ Level 48 - Shadow Ball - Ice Beam - Air Slash - Psychic

Gothitelle @ Level 50 - Thunderbolt - Psychic - Calm Mind - Shadow Ball

So Caitlin from Platinum's Battle Frontier has returned with a vengeance! She's pretty easy to beat too. Most of her Pokemon are fairly slow. Galvantula will be able to spam Bug Buzz while they quiver in fear. For Sigliyph, hit hard with Thunder. Bisharp also works well with Night Slash, but watch out for Reuniclus's Focus Blast.