Don't think that water and fire types are a staple? Or even grass types? look at this:
Kanto: (started with episode 001)
Ash gets Bulbasaur is Episode 10
Ash gets Charmander in Episode 11
Ash gets Squirtle is Episode 12
(i'm not joking, look for your self)
Jhoto: starting with Episode 119
Ash gets Chikorita is Episode 128
Ash gets Cyndaquil in Episode 143
Ash gets Totodile in Episode 153
Hoenn: Starting with Episode 277
Ash gets Treecko in Episode 283 (around the time he got Turtwig, now read this)
Ash gets Corphish in Episode 299 (a little bit later now read
this!)
Ash gets Torkoal in Episode
334 (yeah, that late)
Sinnoh: Starting with Episode 469
Ash gets Turtwig in Episdoe 473
Ash gets water type in Episode ???
Ash gets Fire type in Episode ???
See how far away Ash got Torkoal from when he started? that is 57 episode apart! Sinnoh (Japan) has only gotten 46 Episodes.
I REALLY don't want Aipom to evolve, he is cute, and the Evo is ugly. It's like saying thaty you want Totodile to Evolve. or Corphish.