Why are we having this inane debate? By the end of the day, Blastoise is still a bigger/heavier/stronger/slower version of Squirtle with cannons on its back. Either way, I don't think we are getting a Blastoise/Venusaur/Charizard team. Why would Sakurai want to bother doing that when he could be using the time and resources to develop two or three potential non-clone Pokemon characters like Mewtwo, Meowth, Team Rocket, Zoroark, Victini, Genesect (he's got a cannon on his back), 2nd gen Pokemon Trainer, 3rd gen Pokemon Trainer, 4th gen Pokemon Trainer, and/or 5th gen Pokemon Trainer?
Except, Venusaur and Blastoise wouldn't be in ALONGSIDE their pre-evolutions, and would take just as much time and resources as Squirtle and Ivysaur.
So why should Sakurai waste time and resources making Squirtle and Ivysaur when he can make potential non-clone Pokemon characters like Mewtwo, Meowth, Zoroark, Victini, or Genesect?
Surely he wouldn't waste his time with Team Rocket or another Trainer, as making one Trainer is bad enough that he has to simply keep one Pokemon (Charizard) and dump the other two.
@Diddy, yes, it would make PT an all heavyweight team, but Pokemon currently has only one heavyweight in the history of Smash. Everyone else is a lightweight (even Mewtwo, though he could be bumped up to middleweight) or a middleweight (Lucario only).
Venusaur: 6'07'' and 220.5 lbs
Charizard: 5'07'' and 199.5 lbs
Blastoise: 5'03'' and 188.5 lbs
Venusaur would actually be the largest and heaviest, but not by much. Blastoise is the smallest and lightest of the three.