Gold:
Meganium, Ampharos, Azumarill, Heracross, Togetic, Lapras.
Silver:
Feraligatr, Espeon, Gyarados, Victreebel, Ninetales, Lugia.
Gyarados (regular blue) was later replaced by Riachu when I got to Kanto, and I was able to evolve Weepinbell and Vulpix.