I'm currently playing through blue again, and I have a Charizard, Sandslash, Raticate, Vaporeon, Pidgeotto, and Weepinbell.
Aside from Pidgeotto, they're all fully evolved. (Victreebel is ugly.
)
I'm thinking I should replace raticate with an electric type... although I could just teach it thunderbolt. It's hard to give it up, because I named it after the pet rat I had as a kid. =/