OK, RBY saga: Bulbasaur, Ivysaur and Venusaur were all there, that makes 3, and the whole of the Blastoise line showed up, that's 6, same for the Charizard line, so 9 so far...
GSC saga: Cindaquil and Quilava showed up, didn't see a Typhlosion. 11 so far. The whole of the Meganium line was there, same goes for the Feraligator line. 17 up to here.
Ru/Sa saga: The whole of the Blaziken and Swampert line showed up, and Treecko and Grovyle. Sceptile is yet to make an appearance in the animes.
So, 25 starters in total that showed up in the main stream animes.