Tbh I feel like Megaman has top 3 edgeguarding easily.
He has many tools he can use such as Metal Blade (you can throw it at an angle or you can use it as an item and use it for ZDropping), Leaf Shield, Bair, Dair, and in some cases, pellets.
Personally, I've found the best edgeguarding techniques are holding Metal Blade + Leaf Shield (holding onto ledge and after a hit of Leaf Shield immediately jump and Zdrop the Metal Blade; stage spikes at higher percents), and just using Bair to keep opponents away or to get an early kill.
Also, using Leaf Shield offstage is a very good tool to use for stealing jumps, and footstooling (AKA Leafstooling).
These are just some of the edgeguarding techniques I've found to be most successful in terms of gimping or just getting a kill early on in the game.