Under normal circumstances, don't use thunder. It's fine when you're going for the kill right after an up-smash, but if you're going to try that then you're going to need to get better at aiming it.
I noticed you edgeguarding with a lot of weird stuff, namely thunderjolt and thunder. Especially against someone with an abusable recovery like Luigi, don't be afraid to jump out with a nair or tailspike.
Correct me if Im wrong, but I didn't see you use any shuffled moves. Pikas short hop is somewhat difficult, but its worth learning how to do consistantly.
Don't use dash attack. There's a lot of lag if you miss, and it's just an all around bad move.
Don't smash so much.
EDIT: I just watched the second vid. Try to sweetspot the edge with quick attack when you recover. As Im sure you know, if you quick attack into the stage, you leave yourself very open to attack because of the horrible lag.