Needs moar side-taunt.
Sillyness aside, here's what I think could use some improvement.
Needs moar Blue Blur.
Okay but seriously this time, from your first video I saw a lot of your "recoup" approaches against Charizard were direct SDRs. By recoup I mean like trying to get into a more favorable position after being hit. That's bad, especially when you're going up against ROCK SMASH! as a side-character... yes, it is that good. If you're going to go into ball form at the very least use Spinshots so that you hover over the boulder. If they start picking up on that then feel free to mix it up but I suppose what I just now works for those who love to spam that Side-B.
3:57 You're punishing Charizard's Fly with a forward smash. This would work maybe if you were a little bit closer and if Charizard was at killing %ages. Try FTilting at low %ages, it's a good habit.
4:39 made me sadface. I suppose under pressure most people would probably react like that too, however from what I could see you still had your second jump, and if you were aiming more for the stage than the ledge, you probably still could've made it with the Spring. If that had not worked you probably could've had a shot a walljumping the lip and at the very worst you could've hit Charizard. So many recovery options, too many for me to think of and still mention, don't panic, and just keep your cool next time around.
5:05 Don't worry about fakeouts when your opponent is nowhere near, their first priority is not gonna be worrying about what you're doing on ground unless it's a side-taunt to punish you, just go straight for that Spring into Uair if you must, read where necessary (some like to airdodge, some like to hit you back/to the ceiling, I'm sure you're aware of this.)
The end of that first video needed a taunt to end it in style but I'll let that slide.
Second video you start off with an hyphen USmash... with your opponent on the other side... any reason? I even see you doing this later in the video.
Now this is my personal opinion, but I find rolling/spotdodge near useless with Sonic, I find it much easier to punish my opponents if I just hold my shield throughout the whole ordeal and go from there. You aren't in any immediate danger when you're in that bubble, and Samus's grabgame is not that good... except maybe her pummel which is pretty fast for decaying her moveset but that's besides the point.
3:47 Alright hold it! Do you know how to counteract momentum? Do you know how to momentum cancel with Sonic? If either of the answer is no let me put it this way: Fair -> FF (you might not need this, I don't know) -> ASC = extra time alive on the stage with the stock you're currently on.
Throughout the whole video you get hit by lots of Zairs, I think SHADing works wonders on this, and with Sonic's speed you can usually get away with just shield-dashing. For me I probably get Hella lucky with those Zair PSs and proceed to punish from there.
That last number was a whole mess... I just noticed that and now I think the above applies even more now then I did when I first typed that up.
Third vidja okay here we go.
:27 needed moar DTilts. It may give Sonic 100% damage since DTilts break Sonic but it would've been worth the risk to hit Samus with something right there instead of rolling onto/behind her.
Also don't try to cancel Sonic's jab into anything, it is bad with low/no hitstun, no range, and only 2% per punch with 3% at the kick. Go ahead and add that up on your free time... however I don't want to shun you away from jab,s it does have it's moments... but not at that moment.
At 1:21 you didn't necessarily have to jump cancel the what was then an ASC. It's wierd how the transition works but luckily Infzy here found out that from an aerial Spindash turns to a SpinDash Roll when landing on the ground, and should you take the air again, it turns into an Aerial Spin Charge, and this move is the sex.
4:17
At the end of the video you have learned a very important lesson... HA is bad. If you intentionally used it, you're doing it wrong. I'm almost sure you didn't mean to do it since your flow got interrupted but let's see. You could've shortened it's start-up lag 1/2 if you just pressed the B-button again (don't get any ideas, it's still slow), and you could've moved a bit more to the left to perhaps avoided that UTilt... maybe... I dunno I can't tell HA is crap.
There's mah 2cents, hope it helped.
P.S. for further videos of Sonic please refer to the Winning Steak Cinemas.