You're right. The DK series has lots of great songs, and I think some favourites include Crocodile Cacophony and Pompy the Presumptuous. Really great boss themes, but I do think that it's important the series' music receives a fair share of representation too. Also, (for my Roy Bias) no Winning Road?
Where's the love for my boy, where's his victory theme?
I was thinking about Super Armour for King K. Rool as well. It'd make sense given all that fat he has around his belly. Also, I've noticed something about each of his appearances being slightly different, more than just that tail that sometimes goes missing. If you look at Baron K. Roolenstein's right eye, it's bloodshot, but King K's bloodshot eye is his left eye. Comparison:
I've also noticed that sometimes his belly's gold like armour or it's generic skin, too, as seen in his 3DS trophy. (I think we should also assume that he'll get a trophy in the Wii U version too)