I really miss my team in the first Pokemon game I ever owned, Pokemon Yellow. In it were Hypno, Butterfree, Dodrio, Seadra, Dugtrio, and Dewgong. The Dewgong was Cezanne, the in-game-trade Dewgong. My Hypno was the star of the team; it knew Psychic, Hypnosis, Headbutt, and Dream Eater, and was level 74. That was the highest-level Pokemon I ever had... Unfortunately, the game was deleted when my cousin tried to use a Game Shark on the game...
As far as my current games go, I'd have to say my best is my team in Colosseum. The team is:
Plusle (female Plusle, level 52)
Charge
Spark
Fake Tears
Encore
*I received her from Duking, hence why she doesn't have a nickname.
Poppon (male Jumpluff, level 51)
Mega Drain
Sleep Powder
Cotton Spore
Synthesis
*I start a battle with him 80% of the time. He makes a good Sleeper because of his high Speed. He hardly ever uses Mega Drain in battle, unless my opponent has a Graveler or something.
Skeeter (female Heracross, level 53)
Megahorn
Brick Break
Endure
Reversal
*Ah, the Endure/Reversal combo. Skeeter's my physical sweeper.
Nuo (male Quagsire, level 51)
Surf
Earthquake
Amnesia
Mud Shot
*Mud Shot is there in case I want to use a Ground attack but don't want to hurt Plusle with Earthquake. Fortunately, half my team is immune to Earthquake, so Nuo is useful for hitting both foes at once.
Miyage (female Delibird, level 52)
Blizzard
Present
Fly
Attract
*Delibird is an awkward Pokemon to have on one's team, but for some reason I like Miyage. Her Attract comes in handy sometimes, and she can often stall with Fly. Plus the fact that Blizzard can hit both foes comes in handy.
Voldemort (male Misdreavus, level 52)
Shadow Ball
Psybeam
Pain Split
Perish Song
*It was hard to make Voldemort forget Confuse Ray, but I like Perish Song when the foe's down to two Pokemon, and Pain Split often comes in handy. It's too bad Mismagius doesn't exist in the third generation...