Looked pretty decent.
As Spak mentioned, you took a loooot of damage over the course of the set from recovering onstage. Near the beginning of the set it worked alright, but you could tell the sheik player caught on and would just wait to punish it almost every time. Get more comfortable sweetspotting the ledge. 6:36 made me very happy to see, do more of that. The fair from the ledge afterwards was pretty unsafe, but that's another minor thing.
The combo game was another weak spot, and I'm glad you noticed too. The main thing I saw that could help is it didn't seem like you felt confident in your rising uairs. Take 9:17 for example (it seemed most apparent in the last match as a whole). You shield her bair and rising uair her during its lag, so there was no worry of it trading with anything or getting shielded or sending her at an awkard angle, it was a good setup. And then there was no followup. Rising uair, 3% damage, and then you landed and took a fair through your shield. Rising uair is your opportunity to get a combo started and put the pressure on sheik. Rising uair leads to damage, it's such a good combo starter, especially in this matchup. Even if you just get uair->nair, it knocks sheik away in addition to the damage and gives you stage control.
Those were the main things that I saw. Your pika looked a little slow, not fluid, but it takes a good while for that to come together. You got a couple good gimps and I really like that you were willing to go for stuff off the ledge occasionally, that is often something I don't see newer pikachus do (which is a shame, because it's one big advantage he has over other chars). Even if you weren't fast/precise enough to connect, I could see that you saw certain opportunities and went for them.
Keep it up. Tweak your recoveries and combo game against mid-floaties a bit and I think you're on the right track.