A little thinking...

[FalseFalco]

Pika/pichus neuteral A when pressed as fast as possible, takes 2 frames to execute and start the next. This means at the fastest possible mashing speed you can execute 30 neuteral A's in one second. Im wondering about the shield stun this move has, im guessing the shield stun has much more lag than this move, which would mean if you were mashing on an opponents shield they wouldnt be able to do anything they'd have to get hit and DI away to make you need to move to continue the mashing. If you pinned an opponent against a wall and mashed as fast as possible wouldnt it be a psuedo infinate? they cant shield it for their shield will break, they cant DI away until huge percents where they can DI up and DJ away, they cant CC becuase the attacks are too fast...I realize that in the jump to melee they made characters with rapid A attacks slide away from the wall unlike in SSB, But ive found there is a certain distance where pika and pichus neuteral still hits and you dont slide.

Infinate or no?

[N64]

I think, in that situation, they can DI towards you until they got inside this perfect distance, where your neutral a would start pushing you back, thus giving them enough room to DI away and escape.

This is an 'infinate', however, if you get into a spot where both you and the opponent are buffered by walls. The only two places i know where this exists are on Pokemon stadium: in the nook of the tree, and at the bottom of the rock formation. These, of course, are only part of the stage of the for the short while, so it works until the stage reverts to its neutral form. It is inescapable, in my experience, up until this point.

Edit: oh, and I've only tried it with pika. I don't know if pichu's extends far enough for the pokemon stadium nooks to work, or if it gives the opponent enough room to DI you into the wall, and then DI away.

[Phatgamer1]

Pichu's works as well, but only for a limited time. If the opponent is at fairly high damage at either of these 2 places, they can DI up and away from Pichu and escape. This is due to Pichu being so low to the ground, that his head will not reach high enough to keep the opponent trapped.