Shine.
Shine is bad for everyone offstage, regardless of their physics.
Note: You'd also want to shine them at the top of their bodies, Ganon might grab you if you try to shine his torso and DK's arms protect him pretty well from the sides. You can also use ledge invincibility to burn through their up+B's. Bowser's is pretty tricky to shine, using the edge invincibility would greatly be in your favor.
I would give you more info, but then I'd just be giving you general edgeguarding info, so I'll stick to the shine.
Firefox stall is real great for those tricky shines!
Also, if they're good with ledgeteching your conventional edgeguards like D-smash, bair, F-smash, etc., you can try using drill to throw off their positioning and go for the shine after they mess up.