Very bad quality, but it showcases my overall ability as a Diddy Kong main.
Thanks for posting this.
I don't think that any conclusions you draw at this level would be an accurate reflection of close-quarters reactive gampelay at a tournament level, but clearly the solution is to help you get better
Education and knowledge dissemination are more important than discussing whether Sheik is low or high tier anyway.
You give your opponent a lot of space to maneuver; most of your movement seems imprecise, sometimes aimless. I don't see any empty hop feints, tomahawks, foxtrot dances, or walk-narrowly-out-of-spacing situations. Whenever you're in an uncomfortable position, you seem to roll to reposition, instead of actually using your movement options or spacing attacks. Your opponent in the video seems completely clueless about how to approach the matchup and isn't putting any pressure on you, so you're not seeing the result of these weaknesses. Against anyone who cornered you, pressured you, punished your mistakes, and reacted to your burst options, I think your gameplan would fall apart.
In general, you want to try to feel comfortable staying close to your opponent and reacting to what your opponent does. I don't know about the Diddy vs. Greninja matchup, but Greninja has difficulty up close and should be using his mobility to put distance between you. As the Diddy player, you should be looking to close that gap and then base your gameplan around conditioning dash attacks into your shield (or whiff punishing with banana from a distance just shy of midrange).
Let's look at some specific situations throughout the video.
At the start of the match your opponent is shielding from halfway across the stage for no reason; you shield also and then roll back, giving up stage control. Instead of this, you should see that your opponent is playing passively and seize control of the center by dashing in and starting to set up your zone in the middle. This gives you more of the stage to work with.
At :20 you roll away from your opponent and then try to close the distance between you and Greninja with dash attacks. Diddy's dash attack is alright, but Greninja's is better; in addition, Greninja has shuriken, so what you should have done here is to try to bait an option and respond instead. The Greninja player is fortunately bad and is shielding for no reason in situations where he should also be using his mobility. Since he was shielding so much, you could have pressured him by threatening the dash grab at midrange, and calling out the roll if he rolled behind you in response, as he likely would have. If you don't feel confident calling out rolls, then you could jump, and last-frame-b-air the moment that he rolls (this requires precise spacing); n-air should also work fine if you're comfortable with the distance covered by Greninja's roll.
At :32 you throw out a bunch of rolls because you're not certain of your positioning; there were so many good options for you here, and rolling wasn't effective because the Greninja wasn't jumping at all and so he wasn't committed to moving in a particular direction. In fact, he was shielding again, so you could have just walked or dash danced in front of his shield and waited for an option for him. It was clear by this point that he wasn't ready to punish you with his own dash attack.
The recovery at :44 seemed completely unnecessary; the Greninja wasn't even trying to pressure you off the level. He rolled _away_ from the ledge long before your barrels boosted. You could easily have continued charging and recovered safely to the ledge; another Greninja would have cleanly f-smashed you for your play or even better gotten a short string into a kill confirm at this percent.
At :46 you retreat to the far corner of the stage, giving up all stage control to pull a banana (a losing prospect in this situation), and then you roll behind the Greninja to down-smash, calling out a roll. But your spacing for down-smash wasn't even right so even if he had rolled toward you it's unlikely that he would have gotten hit. Roll -> down-smash looks appealing but there's actually a fine art to using it, and it usually involves pressuring your opponent in the corner. In this situation, however, you were the one in the corner.
At :50 you're in advantage state but you sacrifice all advantageous momentum and run away from the Greninja recovering again to pull a banana. You pull the banana _in_ the Greninja's direction so he could easily have come in underneath you and punished you for this, taking your banana and possibly your stock. For some reason, the Greninja decides to shield, so you don't feel the weight of your mistake.
At 1:05 you repeat a pattern of side-b overhead into land into banana toss into dash to pick up the missed banana. This is likely a habit from smash 4, but it's not effective at all; you're putting yourself above a character known for deadly vortexes, and for what reward? The same mixup can be achieved without ever going behind Greninja. The banana itself creates the pressure that you're looking for. Greninja is so fast that (if the Greninja player were actually using his mobility) you wouldn't be able to end up behind him just using Monkey Flip from full hop height--this positioning gives the Greninja player too much time to react to you. The reason you hit with the side-b at 1:09 is because the Greninja is trying to punish your side-b by meeting you head on instead of safely from below.
At 1:16 you stand completely in place and fire peanuts without regard for where your opponent is; the act of firing peanuts forces the Greninja to take a certain path to get to you, but instead of taking advantage of that path, you decide to roll back again, forfeiting stage control and causing your zoning game to have achieved nothing.
At 1:21 I don't even understand why you'd banana here facing away, but more importantly I don't understand how this Greninja ran into that banana. It was like he looked away from the screen or suddenly acquired the reaction time of an onion.
The next almost entire stock of the match all you're doing is using burst movement--up-b, dash attack, roll, side-b. You don't even jump at all; some tomahawks would have totally enabled you to grab Greninja through that shielding habit and also taken advantage of his complete lack of positioning.
At 1:49 the Greninja is offstage and you're still standing on the far side of the stage as though you don't have any stage control.
At 1:53 you finally take advantage of the zoning game and banana to f-smash his untimely airdodge; this is a good play.
For the rest of the game you continue using un-nuanced burst movement. It ends up working because your opponent is shielding with a character who doesn't have good out of shield options (and that too is doing so from half a stage length away) and trying to aggressively dash attack your burst movement options with a character built to bait and punish.
I have no idea why he was trying to Substitute your peanuts instead of using his mobility to get back on the stage. Either that player doesn't play smash much, doesn't play Greninja much, or was trolling. But regardless of the other player, you can see even from this short video where you can start to optimize your movement. Get rid of excess. Don't dash when walking suffices. Firmly but cautiously take stage control when you can. Hold your advantage and wait for your opponent to act instead of dash attacking and hoping that it hits. These things will improve your gameplay immensely.
