you'd be surprised how easily you get people to think pichu is all about d-tilt, jolt, running, and nair mix-ups and you can up-B through their wall and up-smash them to nothingness. it's very fun vs puff who's like geuss wut? bair wall. Pichu is amazing for tearing down walls because of his speed, size, projectiles, and up-B. Really walling pichu is a terrible idea compared to just rushing him.
I really don't think you can wall pichu out like they're ice climbers or someone somewhat slow.
Also watch for some moves like at low percents you can CC stuff into up-smash it's a nice slap to the face.
match-up I feel I know best ways to kill
Captain Falcon- Any is good really grabs, edge gaurd, combos to kill moves are all great
Fox - any thing you can land really 40% nair->jab reset->f-smash->**** up-air to whatever till 60% after you must follow up with a move higher than when you hit fox.
Mario- up-smash is very risky I think killing at like 150% with nair is seriously the best way to deal with him.
Pikachu- he miss you up-smash or whatever bair/jolts(early recovery like knock out 2nd jump) edge gaurd for best results.
Sheik- You'd be surprise by the up-smashes you can get edge gaurd is a must.
Falco- same as fox but it's easily to start combos, sheild pressure, and get grabs like maay falcos love to dair your sheild and land behide you you can normally grab them before they up-tilt your sheild it's sooo funny I once got 3 backwards grabs in one match and that's the only way I could get my grabs.
Ganondorf- bair/jolt recovery up-smashes to thunder are nice meatly hits. you'll be able to get up-smashes trust me.
Jigglypuff nairs jolts and perfect ups to up-smashes never f-smash over 25% anystage fully charged side-B ends puff think missed rest does 39%. nearly always best option. up-smashes kill at insane percents.
Marth like puff more up-smashes due to CCing some moves and you can f-smash somewhat safely.
Pichu- can't land anything really if they're smart and patience you could freakin time out there's no solid anything other than pray mindgames work. I'm very seriously but up-smash are fun. These matches take me longer than puffs even when the puff is on a much bigger stage trying to camp.
Really pichu's killing problems aren't that bad.