4 Ideas:
Character Barrel
Funky Kong
Cranky Kong
Secret, read to find.
I was thinking, just like the Pokemon Trainer in Brawl, there could be the Character Barrel from DK64.
Inside the Barrel we have:
Tiny Kong
Lanky Kong
Chunky Kong
Now these characters should be similar to Squirtle, Ivysaur & Charizard respectively.
Tiny does hair flicks and kick flips. She is small and fast.
Lanky does arm stretches to reach distant foes, if they are still far he has a blowgun. He is average with speed and can do basic damage.
Chunky should have boulder smashes and a pineapple launcher. He should be quite slow and heavy, but do serious damage.
Final Smash would simply be a Jazz Band performed by the trio. Lanky with his trombone, Tiny with a saxophone and Chunky with his triangle.
Next up: Funky Kong.
Funky seems to look like a complete clone of DK except that he has a large use of guns. All Specials should be junglified-gun related.
Cranky Kong should be a slow, but light ape. He should have heavy type attacks but take damage easily. Specials should be the potions he gives the player in DK64, like the down special could be the Buttus Bashium potion.
Dragon Dragonfly AKA Diddy's Boss
The dragon dragonfly is one of the most fun bosses in DK64. It would be cool to play as her.