what I meant by "pika has a crappy side b" is that it doesn't go far or help his recovery very much, imo.
Pichu's SideB goes much further and helps a lot more than pika's. It helps to make up for the fact that his upB can't travel as far.
SideB can do some stuff as well... Its an amazing Puff punisher, should puff miss a rest (kills at 13% or so on FD, which is faster than Pika's will, iirc). You can also ledgecancel sideB...
anyways, agility, while it has uses, is certainly not pichu's "shine," if anything, his shine would be his Nair or maybe even Dtilt. Nair is Pichu's best move. Its an effective and reliable approach (agility is not), it combos and gimps, and it is pretty safe on shield (late nair).
You shouldn't be using Agility too often. Its a gimmick. Its nice when you get it, but a decent player can pick up on it and just react to it. Its not particularly fast nor is it very safe. Its more of a risk reward kind of thing, but you don't want to be throwing that out too often. Only when it will be a good option and probably won't be punished. Its never a safe approach.
His usmash sucks when you hit stuff behind you. - should have used d-smash instead
you can't dsmash OoS.
also, arguing is fun. It makes me think about the character more, which helps me learn more about him.