Hi HudnofskiBlue, I can explain how I usually edge guard with Pikachu. It varies based on the character I am up against for one. Some characters recover up high, down low, side ways, or anyway they feel like. In my personal experience the up high and down low recovery attempts are easier for my Pikachu to edge guard.
T-Jolt edge guards are easy and safe. Let them dive diagonally down on your foe or let the hug the stage. The hugging ones zap foes on the ledge or ones that have to
recover vertically from below. However imo, both methods are lackluster at taking a stock, but it will get the job done sometimes and free damage is still nice.
Simple
Aerials work well for Pikachu. Bair can stage spike or drag the foe down. (This one is hard to hit with for me atm but is consistent for other players with more practice in.) Fair can push foes outward. Nair can also push opponents out further. Dair can be deadly if used properly. Aerials are good for attacking each kind of recovery, but they seem to be our best bet against
mid height recoveries.
Thunder can be brutal as an edge guard. I try to either spike with the cloud hitbox, hit with the invincible melee hit of Thunder, or both if the natural combo works. Thunder is at its prime punishing
high recovery attempts.
I hear
Quick Attack can also be used to edge guard by disrupting second jumps and flinching opponents when they do not expect it.
Personally, I like to
punish ledge get up options and stage landings the most. It requires fast reflexes, a read, or a bait/set up. The key is to pick up on your opponents habits. Which option is their default go to? Which option would be the best one for them at that moment?
1. The opponent can get up normally. You can punish this with Up Smash or spaced F-Smash usually. A jab is both really funny and effective too. The jab usually forces the opponent back to the ledge while netting free damage.
2. The get up attack. Go for an easy shield grab.
3. The jump get up. Allows a hard Nair or Uair chain.
4. The roll get up. Allows pretty much any follow up.
5. Ledge drops into aerials. These are a mix up you need to watch out for. Usually you can punish with a shield grab though.
I hope this gives you some ideas to work with and good luck!