A'right, I'm just gonna watch the vids in order and post my ideas here as I watch. This will be sorta stream-of-consciousness because I'm feeling lazy.
First vid: You're upsmashing too much while Zelda has low percentages. It's a viable kill move against her since she's not that heavy; don't make the move stale such that it loses killing power when you really wanna use it. Wow, she's spamming aerials and you keep jumping into 'em and getting pwnt. If you can't time a Fair properly to get past the Bair spam (which is to be expected considering the relative range of Zelda's Bair and Oli's Fair), you're better off sitting on the ground and using an Up-B to counter her when she jumps, or rolling behind her and Fsmashing as she lands. Considering your friend's constant aggression when the two of you are close, you should be dodging and shielding much better than you are; Zelda keeps attacking and you sit there shielding and taking several hits in a row. When you shield a ground hit, immediately grab from it; when you shield an air attack, Up-B to counter. You're being very predictable as you fall; try DI-zigzagging as you land and suddenly choosing a direction in the last second of falling to get away from her, or other mini-mindgames, or else you're gonna get yourself side-KOed as you fall -- yup, there you go. Wow, you pulled all your Pikmin as you spawned and she killed half of 'em with a Bair. If your Pikmin are separated from you and she's going for them, either Whistle to get 'em back or just use the opportunity to attack her while she's busy stupidly attacking your Pikmin instead of you. Heh, see, that Usmash shoulda killed her at 100% but you diminished its effectiveness by using it twice earlier. You keep falling into that Usmash; she doesn't slide that much when she does a dashing-Usmash in comparison to most characters, so you really should be able to DI to the side and air-dodge past it, but you're trying to air-dodge straight down past it, which isn't working. Gah, you died to a sweetspotted Bair at the end again; that Bair spam is really getting predictable by this point, so you should just be backing up and throwing Pikmin to punish him if he's gonna sit there and keep doing that, until he learns his lesson. Wow, does your friend EVER try throwing? You shielded the entire time during that match instead of dodging, yet he just sits there and keeps attacking. He needs to learn how to grab (and maybe he should B-stick if he's gonna be doing so many aerial Din's Fires).
Second vid: Jeez, Bair-spammed off the stage and then edgehogged. You really need to learn how to counter that Bair spam, huh? It's not easy to counter a quick Bair by a Zelda, but Bair _spam_ is different because it's predictable. You should be able to roll/dodge/powershield that or just jump backwards and hurl Pikmin at her until she realizes the futility of her useless charging. Huh, your friend didn't edgehog you that time when you were at 54%. Gah, sweetspotted Bair; that ****ed thing should be getting stale by this point with the rate at which you've walked into 'em. Do you do a Bthrow _every_ time you grab her? Try Dthrowing; it leads better into follow-up attacks such as Fairs or even just a standing Up-B if you're feeling lazy (like me). Plus, the Bthrow is a viable kill move with Blue Pikmin, so you don't wanna diminish its killing potential. Oh, I see your problem now! You ARE trying to throw Pikmin to counter the Bair, but she just kills them with the Bair itself. You have a few choices: time it right so that doesn't happen, aim it right so that doesn't happen (easiest with a Yellow Pikmin, which travels in an arc just over her leg and latches onto her head if you jump before you throw), or keep throwing, failing to get the Pikmin through, making him expect you're going to keep doing that, and suddenly mixing things up with one of my earlier suggestions for beating the Bair (standing Up-B, roll past and Fsmash, jump/air-dodge over and Dsmash, etc). I'll have to test, but a Purple Pikmin might outprioritize the Bair. Actually, the funny thing is that Zelda freezes for a bit (not as long as her target, but a bit) if she sweetspots a Bair. Throw a Pikmin at her attack and you might be able to take advantage of that time during which she's frozen. I'll have to test that out later. Gah, you're getting outprioritized by her other aerials too. Try Nairing; that's a surprisingly high-priority move in Olimar's arsenal. Ouch, edgehogged again for the win. You don't DI upwards enough to make it easier to reach land without tethering. DIing upwards should become instinct with Olimar.
Third vid: Got her off the edge nice and early there, but then let her back onto the edge with predictable aerials. Mix up your game; again, the Up-B is an amazingly under-used move. When people are trying to recover, they watch and wait for Olimar to jump and start using aerials to edgeguard, and they react to that, just as your friend did. The last thing they expect is for Olimar to sit there and suddenly do a standing Up-B in their faces. That would've knocked your friend away without a double-jump, forcing her to Up-B back, which isn't hard to edgeguard; you had a Purple Pikmin coming up next with which you could've knocked her away, and her next Up-B would've had to target the edge and would thus have been edgehoggable. There you go again, shielding the Din's Fire and then putting down your shield just as she hits you in the face with a standing attack, when you should've just grabbed her from the shield as she tried to approach after Din's Fire. Wow, your friend starts off with the Bairs JUST as you've spawned! I personally would let him land a few Bairs (getting in damage as I do so with latched Pikmin) so that the move gets stale and then start attacking; he wouldn't be able to get a Bair KO at that point (aside from a sweetspotted one), and he's very predictable when using his other moves, so those are easily shielded and dodged. Ugh, yeah, you used an Usmash when it couldn't've killed her, so then the second one you did failed to kill her even when it should've. When she was just behind you, you'd've been better off Dsmashing. You don't ALWAYS have to Usmash when running, you know; grabbing is probably the best thing you can do against, speciifcally, your friend, who tends to sit there and try to keep you away with close-range attacks when he sees you dashing, or you can stop your momentum by shielding and then do any move in Oli's arsenal, or you can even do a dash attack, since Oli's is surprisingly quick. Huh? Why'd you try to WAC that attack (and fail, thus ending up vertically-KOed)? You could've just air-dodged it. Why WAC when you can dodge? WACing is only useful if you wanna counter-attack more quickly than a dodge will allow; you were in no position to counter that attack even had you successfully WACed it.
Fourth vid: Good first stock. Good attacking in general; you timed your attacks properly to counter his attacks and dodges for once. Guess you were getting the hang of him by this point? Ouch, you tried to WAC the Usmash again, and then didn't DI properly. Jeez, there it goes again: you start throwing Pikmin and he just sits there attacking and killing 'em. That pattern happens so often, even at close range like here, and you need to just break that pattern by suddenly dashing in and grabbing. Haha, there we go: in three seconds, two of the things I'd mentioned previously just happened...You shield-grabbed him after a Din's Fire, and you attacked him while he sweetspot-Baired a Pikmin. ^_^ Yeah, you really need to mix up your dash game a bit more; I can't recall a time I've seen you approach via dashing when you weren't planning to Usmash.
Last vid: Jeez, your friend just sits there using Din's Fire and leaves himself completely open. It's hard to punish Din's Fire at range _after_ it's over, yes, but before the fireball reaches you, you should latch a Pikmin onto Zelda. Then she either has to cut it short and get the Pikmin off, or try to hit you (and you should shield anyway, making it futile) and take some damage. You either get some damage in or you get a chance to start approaching. *gasp* AEYR GRABBED HOLY ****. Anyway. Grr, you're spamming Usmashes again, not even while dashing anymore. I bet you're going to need it soon and it won't kill properly. You had a five-second battle of spot-dodging and rolling which you could've easily ended by throwing any Pikmin but White (so that it moves slowly enough that it will hit even if they roll) or by doing a dash-grab (which has enough range to hit even if they roll). You walked into your friend's Farore's Wind recovery even though he's recovered to that exact same point EVERY time except one; expect it, stand there and shield, then punish.
Sorry if that's overly critical (if you can understand any of it), but I didn't mention any of the good things you did, and there were plenty.
Anyway, basic summary, then: do things out of your shield, especially shield-grabbing, rather than just putting down the shield calmly and waiting to get smashed in the face...incorporate standing Up-Bs into your arsenal more often, as they're quite surprising for most people and they're a high-priority, long-range, easy method of cycling through your moves to allow others to recharge from the stale move effect...don't use Usmashes so often, even while dashing, because you're weakening its kill potential for when you need it (not to mention becoming predictable)...start grabbing more often (which ties into my point about increasing your dash-in options), and use Dthrows when you do so as to allow the Bthrow its killing potential if you get a blue and in order to set up combos...get a couple grab attacks in when you grab, since there's no reason not to do so and White Pikmin hurt like hell when they land grab attacks...and finally, for Aeyr-specific tactics, you need to learn Aeyr's patterns such as the Farore's Wind recovery spot, the tendency to alternate between purely offensive approaches (dash attacks and Bair spam) and extreme camp (Din's Fire spam and standing attack spam) without any in-between game (such as an approaching Din's Fire --> shield-dash --> smash), etc, so that you can shield/dodge his attacks more consistently and counter 'em...
Crap, parents, gotta go and this post is too long anyway. Have fun.
). I'm just gonna say what i'd try to do against some of his (your friend, yes i know zelda is a girl 
) tactics. In giving u suggstions, i'm not saying i'm the best at this game and that i'm so much smarter than u so don't take it that way please.