Sure, anything for a marathon:
1: Venusaur, Lapras, Gengar
2: Tyranitar, Scizor, Heracross
3: Milotic, Medicham, Gardevoir
4: Dialga, Togekiss, Empoleon
5: Excadrill, Mienshao, Lilligant
6: Aegislash, Greninja, Talonflame
Steel and Water happen to be my favorites and one of these Pokemon has both types. For having one of the weaker selections, generations 2 and 3 are the ones with honrable mentions (Lugia and Salamence.)