Am doing fine. Diddy is my only character in Elite Smash. What you need to remember is that Banana options are more diverse this time around.
Forget that shield, you gotta play bait & punish now. Be more of a evasive grappler, Banana throws a longer distance now and you can easily get a grab in whenever you punish someone with Banana Throw. Build up damage by doing double B Airs after a D Throw, and; PUMMEL! It's crazy fast now. Also, you can throw the Banana out of the air to a grounded enemy, and follow up with a Smash attack for the kill. It's good for catching them at surprise!
Also Monkey Flip is still highly usable, the Kick part of it now kills again. So that's good. It can kill around 150% near the edge, unless you deal with anything heavier than say, Link. Whenever at higher %s, D Throw is best followed up with F Air.
F Smash kills way earlier, and it's the MOST reliable KO option, out of Banana it's all but a confirmed kill. It'll be great for the first 2 stocks maybe, but rather predictable on the last one. Don't rely on it too much for players who figure out your plan. Mix up Monkey Flip Kick with the regular command grab when a player starts shielding a lot. Pummel a lot, F Throw and B Throw deal quite good damage and can kill around 200% (you'll need this at times, believe me).
Peanut Popgun is also great for "edgeguarding" on stage. You'll generally want to deal chip damage, any % is good for us.
The Rocket Barrel Jetpack now explodes WAY more reliably as well! This is a great thing, because it gives us a way less predictable KO option. D Tilt to U Smash doesn't quite work anymore, but U Smash can still kill after a Banana Throw. Anyway, Up B kills and crashes way easier. It's a good thing to trade off at times, just arc the Rocket Barrels exactly at the place where your enemy stands when you try to recover and hit the ground with Diddy's head (cruel it seems, but it only does 5-6%).. I call this Kamikaze Kong. It kills mid heavy characters as Mario and Wolf around 155% or so, lighter characters earlier.
So I guess there's your plan. Dash dance, throw out a banana, wait till the enemy is punishable; throw banana -> pummel pummel -> D Throw -> follow up with B Air x 2 or F Air and possibly follow up with Monkey Flip Kick or Peanut Popgun if your enemy allows it, and sort of repeat. Diddy builds up damage like crazy here. A combo like this easily deals 40+ damage, and you'll reliably keep doing damage untill kill % if the enemy doesn't figure you out. F Air is good for edgeguarding, but don't take too high risks. Best to stay on stage most of the time.
It's indeed a bit different to get used to, but believe me. Once you get this new playstyle, you gonna have lots of fun with Diddy.
Final words of warning: don't look at the %s and feel comfortable whenever you are in the lead. We are heavily punished with combos and nerfed weight and nerfed recovery makes it easier for the opponent to land KOs. If you can't kill with banana confirms, try Monkey Flip or F / B Throw near ledges.