@Megamang
Tagging you here because I'm like 6 pages behind on the Competitive Impressions thread (I'll catch up eventually, and probably address this there, because I see a lot of misinformation about the chimp in that thread) but I thought I should reply to something you said/asked about Diddy's upsmash.
Dtilt upsmash is basically mixups upon mixups for Diddy. First of all, the things
Browny
said are true, you
should be avoiding the upsmash (aside from potentially during a VERY small percentage window) if you're getting hit by close to max-spacing dtilt and airdodging, particularly if you successfully manage to DI the dtilt not-terribly (eg. stop running in to Diddy). Diddy-side counterplay to this is obvious (bait airdodge) but it's still a huge blow to his high-percentages endgame, and may affect his viability quite significantly if people start doing it consistently. Diddy Kong could go from Mr. Consistently Ends Your Stock At 140%
(which as an aside is QUITE LATE) to a character that struggles to kill a little bit when his opponent avoids doing dumb things near either the banana or the ledge. This is the first, most obvious layer of mixups and counterplay from both characters, however if you get hit by dtilt at close range you're still dead, right?
The second and third layers of avoiding the dtilt upsmash kill confirm are very closely linked: DI and SDI. Firstly, dtilt is very quick, so it's not possible to always DI the move correctly, however there are a lot of subtle opportunities when you should be preemptively DIing in anticipation of the dtilt (endlag, landing lag, etc. particularly after hitting Diddy's shield) and one very important one - after getting hit by a banana unless you're right by the ledge or at very high percentages you should be able to react in time and DI the down tilt successfully. This is huge, because every Diddy alive goes for banana dtilt upsmash, and now you can neuter it. The conventional "good" DI for dtilt upsmash is up and away/away, however Diddy can still usually catch you by doing a "long" dash -> jc upsmash. This is where the final piece of the puzzle fits in.
The Diddy player doesn't have time to react to your DI after dtilt (not
really), so he'll likely go for the "long" dash -> jc upsmash to cover the more likely escape option. If you DON'T DI away but the Diddy player thinks you will you've been handed a golden opportunity to escape the upsmash, by SDIing up and behind (through!) Diddy. It's relatively easy to react to being hit by dtilt and preemptively SDI out of the upsmash. If the Diddy player begins to catch on to this, he can do a "short" dash -> upsmash which (usually) beats the up and in SDI, but leaves himself vulnerable to up+away SDI, and if you manage to DI the dtilt not-terribly the upsmash will whiff entirely.
tl;dr diddy sux if you mix up your DI and actually attempt to SDI upsmash
Edit: I also like what you wrote about the Mewtwo MU Megamang, it's definitely not as bad as people think it is for M2.