Let's narrow the list down to only first evolutions.
- Pichu (not Kanto but the pre-evolved form of Pikachu; this Pichu knows Volt Tackle)
- Nidoran♂ (eventually Nidoking)
- Vulpix (becomes Ninetails)
- Venonat (Venomoth)
- Poliwag (Poliwhirl)
- Gastly (Haunter)
- Hitmonlee (or Tyrogue, it's one of Tyrogue's three evolutions)
- Rhyhorn (Rhydon)
- Chansey (or get a Happiny, it evolves to Chansey)
- Elekid (becomes Electabuzz)
- Magby (Magmar)
- Mr. Mime (or get Mime Junior)
- Dragonite (covers all three in chain)
That is a heckuva long list! I do know I can cover the following: Bulbasaur, Charmander, Squirtle, Caterpie, Pichu, Nidoran♂, Vulpix, Paras, Poliwag, Machop, Geodude, Magby, Dragonite.
Dragonite is in fact found by fishing around Dragonspiral Tower, Geodude can be bred from Graveler found at Challenger's Cave, Paras I think is the Route 11 White-exclusive swarm (I traded for it), Poliwag is a Route 6 fishing find. Most of the rest I had to trade for.
Give me some time to look over my list and figure out what I need, Kanto is on my own completion list right now as well. I do know I need Minun from the Hoenn region, however, a White exclusive I have yet to receive.