well, even with one from each type, its very hard to choose, but here they are.
Normal Zangoose for sure, although Staraptor is definitely a close second
Grass: Sceptile, he's so awesome, but again, Ludicolo is a close second
Fire: This is a hard one, but I'd have to go with Magmortar
Water: So many water pokemon, but the obvious choice is Swampert, a close second would be Sharpedo and kyogre though
Electric: Electabuzz. My first ever electric pokemon
Ground: Gliscor, he's just so awesome. One of the good sinnoh evolutions
Flying: Salamence, the coolest flying pokemon for sure
Rock: Have to go with Tyranitar. Awesome dinosaur
Fighting: There's not to many fighting pokemon I like, but I'd have to go with Blaziken
Psychic: Deoxys, with Slowking and Gardevoir close behind
Bug: Another type that I don't like that much, but it be a close tie between Scizor and Scolipede
Poison: Nidoking, Skunktank, And Toxicroak are all pretty close, with Nidoking slightly surpassing
Ice: Weavile, it recently surpassed Cloyster after I used it in Black 2
Ghost: Gengar for sure, although Sableye is also Awesome
Dragon: Hydreigon is actually my second favourite dragon(I had to put Salamence in the flying category), although he's still awesome. Garchomp's cool as well
Dark: A three way tie between Darkrai, Bisharp, and Cacturne. All really cool pokemon designs in my opinion. Dark is an awesome type
Steel: Another of my favourite type's. Jirachi, Aggron, and Empoleon would be tied