RE: In-game Team Rates
Here is the team I used to beat Platinum:
Chomp (Garchomp) lv 100 @ Muscle Band
Sand Veil
Earthquake
Dragon Claw
Fire Fang
Crunch
This beast rips through most Pokemon that aren't prepared with Earthquake. He evolved just before Volkner, so I owned him rather well. He has Crunch to deal with Psychic types that try and take advantage of his low(ish) Sp.D. Dragon Claw over Dragon Ruch because accuracy matters in-game. Fire Famg for the Ice types that try and hit him for 4x SE
Blade (Gallade) lv 100 @ Razor Claw
Steadfast
Leaf Blade
Psycho Cut
Night Slash
Close Combat
This guy beats Medicham any day. I ran Shadow Claw over Night Slash for a while, but I like Night Slash more. He's not fast, but he spams the hell outta critical hits with Razor Claw. He can take three Shadow balls from Alakazam and two from Gengar, then OHKO them with Night Slash (Alakazam) or Psycho Cut (Gengar). I evolved him before Wake, because I found a Dawn Stone in that muddy place West of Pastoria. Leaf Blade kicked butt.
Raptor (Staraptor) @ Sky Plate
Intimidate
Fly
Brave Bird
Close Combat
Steel Wing
I needed a flying Pokemon, so I chose Staraptor over Crobat. Sky Plate allows it to deal massive damage with Brave Bird. Steel Wing and Close Combat are for Rock and Ice types that get in my way. Intimidate helped me to cut Cynthia's Garchomp's attack so that Empoleon could survive an Earthquake and Ice Beam it. U-turn wouldn't be too bad on this set.
Pinguin (Empoleon) @ Wise Glasses
Torrent
Surf
Hydro Pump
Flash Cannon
Ice Beam
This thing is so hard to kill. It survives just about any SE move, unless it's STAB, and reteliates with Surf for its own STAB. This guy ran rings around Roark, Byron, Bertha, and Flint. He's been invaluable throughout the game, and was my only way to guarantee an OHKO on Cynthia's Garchomp until my own Garchomp outsped it.
Rapid (Rapidash) @ Expert Belt
Flash Fire
Flare Blitz
MegaHorn
Bounce
Poison Jab
The most fun way to sweep Lucian. MegaHorn Mr. Mime, Alakazam, and Espeon. Bounce Gallade. Flare Blitz Bronzong. He's there for that, mainly. He's fast and sweeps Psychics like you wouldn't believe. Expert Belt is for added win.
Syke (Alakazam) @ Lum Berry
Energy Ball
Shadow Ball
Focus Blast
Psychic
In reality, the only things this has to worry about are Spiritomb, Sableye, Stunky, and Stuntank. Everything else it hits for SE or STAB Psychic. Out of my 14 lv 100s, this is the fastest. Lum Berry is his BT item that suits him just as well out of there.
This lot did very well for me ingame, and I had all the necessary pre-evos before the 3rd gym.