First of all, we'll start off with known Pokemon:

Arcanine
Nidoking
Krabby (A humongous one)
Eevee
Doduo
Dodrio
Nidoqueen
Golem

And then there are some Pokemon that we think he has, but don't really have evidence to back it up. We'll start off with the Matos' Pokemon Special #5:

Charizard
Scyther
Golduck

Now we can go on to Toshiri Ono's:

Venasaur
Gyarados
Rhydon

The big debate: Who was Shigeru's starter? For some reason, Nintendo announced Bulbasaur as the best starter. In my own opinions, I think Charmander is the best starter. Later, he evolves into Charizard, which is one of the most strongest. He also gains experience faster. In my opinion, Bulbasaur gains experience too slow for my tastes. If you saw the Tajiri pictures in the gallery, in every picture Shigeru was in, there was a Charmander behind him. Look at this pic. May has a Squirtle behind her, Shigeru has a Charmander behind him, and Satoshi had a Bulbasaur behind him. This picture is also directly from Nintendo. Shigeru said he had got the best starter, but it could've been in his own opinion, not Nintendo's.