You can chain grab pikachu with jump canceled grabs after down throw. You wave dashing is decent, but you don't seem to be using it at the right moments, but the only way to learn that is through experience so keep doing what you are doing.
Tips:
1.) I find that the safest thing to do from the ledge is either a. stand or b. drop off jump and waveland, practing this will cause suicides of you aren't very good at it.
2.) Nair is an excellent combo starter. Great priority. Pops up enough for fair or dair or more nairs. I hit full jump nairs into falling nairs into full jump nair into double jump down air for people who DI bad. You seem to lie to land with fair or dair. Mix up a few nairs in there.
3.) Edge guarding. You go straight for the ledge. especially against pikachu you probably want to stay on the stage until he is below the cliff horizon. Otherwise he has the whole stage to safely land on. Mix it up a little.
4.) Off stage. everything was decent except your up+b's. Try and sweet spot the ledge. Save your jump until after the forward B and if you can use the tornado.
5.) There are very VERY few times you should dash attack.