How do you edgeguard with Pikachu?

[Sneak Sneaks]

I dropped Megaman as my main a while ago and now I main Pikachu. Everything is fine with him but, how do you edgeguard? Specially Yoshi??

 

[Emuchu]

It's hard to edgeguard Yoshi because of his armored second jump, which he'll try to use to blow through your attempts to interrupt him. Yoshi tends to do a few things:

• Super-jump over the stage!
  • This is pretty tough to deal with because Yoshi keeps all of his options on the way down, including his Nair, SideB, B-reverse NeutralB, and that little float from UpB. I usually just wait for Yoshi to land and try to intercept him with OoS Utilt, OoS Grab, or Pivot Fsmash, but you can try to Uair or Fair him if you're good at spacing around Yoshi's Nair and Bair.
• Super-jump for a ledge-snap!
  • There isn't much you can do to interrupt this, but what you CAN do is jump out there and try to peg him before his second jump comes out. Pikachu can go all the way out into the blast zones and still recover, so as long as you don't eat a Fair spike, you should feel free to jump out there with Fair. In addition, you can attempt to ledge-trump Yoshi, except that Pika doesn't have any particularly strong punishes out of a trump, so perhaps you should just wait for his recovery option.
• Super-jump onto the stage with an attack!
  • Yoshi landing with Nair is pretty strong, and the really daring ones might try to Fair you into followups, or ledge-snap-release-Uair. You can challenge this with SH Dair AC or Pivot Fsmash as they're coming in, or you can just shield-grab or OoS Utilt him.
• The Super-jump isn't enough and Yoshi needs to UpB!
  • If you knock Yoshi so far back that he needs to UpB to recover, then you can apply the full gamut of Pika shenanigans, including Thunder-spikes, B-reverse Thunder walls, run-off Bair, or run-off Nair. Watch out for that egg, though, you want to interrupt him as he's throwing it and not walk into the egg.

TL;DR: Pika's edgeguarding power comes from his ability to just go out there and press buttons without regard for his own safety, but you have to play around Yoshi's armored Super-jump and try to tag him before or after he uses it, and not during.