I certainly agree that swapping is the more effective playstyle if you can learn to play all 3 of the Pokemon. Also, when I say shield+special to change, I really just mean the button for shield. I don't mean you have to be able to put your shield up. So the input is, specifically, L/R+B, which you can still do in the air.
The character is very clearly designed to have all 3 used in tandem. However I mainly disagree with the idea of the forced switch between stocks. Perhaps Squirtle is still best for the situation, I don't think you should have to waste all your invincibility from the respawn platform switching back around to him. As I said in a previous post, it feels like an unnecessary homage to being forced to switch when a Pokemon faints in a Pokemon game, and I think it just makes the character naturally worse. I'll switch when the time is right
I wish they created an input to switch so they could open up 4 specials for each Pokemon, but that's hardly my issue with the character.
It's crazy that answering the question about the input turned into all this