Best costume
DDM: "I Will Survive" is acceptable here, because it's Cake. :D (I dunno why he used it twice though, haha)
KillerSOS: Like everyone said, GRAB MOAR.
Olimar has the best freaking grab game in brawl. Range, Combos, KO power. Don't listen to anyone who calls you a grab ***** or a spammer, you have every reason to abuse those grabs, lol.
You could have just grabbed Zelda right at the start instead of using that fsmash with a white pikmin. The grab would have led to up smash/fair/nair and the combo would continue from there. Also, fsmashing with that white in line shows you're not looking close enough at your pikmin lineup.
Try whistling for that purpose and the purpose of defense and countering. You'll see the term "WAC" here (I just call it whistling personally ;p) which is "Whistle Armor Counter" as in using the super armor frames from your whistle to take the damage of the attack and immediately counter attack during the lag of your opponent's attack.
Whistling can be a better defensive option than air dodging against certain moves with hitboxes too large and too long to just air dodge, like that IC uair you got juggled by. You shouldn't get juggled by that IC uair, lol. You can just whistle it and get to the ground again/counterattack
In general though, you need work. From your videos you seem to play based entirely on your position and your opponent's position without much thought or prediction. As in, you use fsmash when they're so far away or running up smash when they're up and away, ect. Which is fine until it becomes anticipated and then it becomes a game of predicting your opponent.
It's an easy habit to fall into but once you're out of it, it's a significant sign of improvement into a better player. Keep at it dude. =)