I like a balanced lineup. Consists of:
Blastoise - always gotta go Squirtle in the beginning
Flareon - not really a good fire Pokemon until you get Eevee
Raichu - since you can catch a Pikachu early, its better than getting a Zapdos late
Weepingbell/Vileplume - grass, Pokemon depends on red/blue
Gengar - given, gotta go ghost
Alakazam - another given