Ever since DKCR, I'm thinking Diddy might get some changes. I don't know why Diddy has so few people discussing him... It's actually kind of heartbreaking to see the character I wanted in so badly in Brawl rarely getting discussed.
Specific tripping with the Bananas could stay. I see no problem with that. Other attacks could cause tripping to maybe.
Changes DKCR could influence on Diddy's moveset could be on his Jetpack and Down B. The Down B could be like DK's Ground Slap, but called the Popgun Pound, causing Diddy to shoot with both his Peanut Popguns opposed to using just one. It has a stunning ability in DKCR, so it could be the same here.
The Barrel Jetpack could function as a sort of glide, or more like R.O.B.'s Up B in a way. Would like if it was possible to shoot Peanut Popguns to while doing this move, or in general, do moves out of it. Making it a good approaching attack to. Overall I really like how Diddy's moveset was in Brawl! Have no complaints about it, even though I had to get used to the heavy Banana playstyle, and Diddy having so little tail-based moves.
Would like it if they made Diddy a little more powerful in his attacks to. Sure, you might think a Top Tier Brawl character doesn't need buffs, but Diddy has quite evenish matchups throughout the cast, which is unique for a Top Tier character. However, think what made Diddy a Top Tier character mostly is Brawl's physics and his Bananas. It's a golden combination, but I doubt he'll be as effective in Smash 4 as this. Thus a few buffs shouldn't be too weird. It'd like more ranged attacks using Diddy's tail to.