Wave 5 is awesome! I'm particularly excited for Daisy Cruiser. Its a fan favorite, and its actually my favorite Double Dash track. I'm also excited about Kamek, Petey and Wiggler being in as it'll had more variety to the game I'm not glad they aren't ramming all koopas in the game. Imagine if we got Chargin' Chuck, Hammer Bro, AND Kamek? I would've been pissed.
As for the character predictions for Wave 6, I'm seeing a lot of people say it'll be Pauline and either Funky or Diddy. Make no bones about it, Funky is a popular character, but that's not really a good enough reason. When I was younger and played MKWii, I sort of viewed Funky as a "joke" character who took Petey's spot. Funky, while he is own monkey, is similar to Cat Peach and Tanooki Mario in that he's essentially DK in clothes. Nintendo in the past always has and always will view Diddy Kong as second fiddle to Donkey Kong in any game he is in, if they have to add another Kong to a game.
I can't think of one instance where, if Donkey Kong was in a spin-off Mario game, that another Kong took Diddy's place. They only time this happened was in Mario Tennis 64 where it was Donkey Kong Jr. as the "second" Kong but that was in 2000, and Diddy started appearing in spin-offs regularly in 2003. One of two things happen in spin-offs: Either Donkey Kong is playable, but Diddy isn't and no other Kong is (like for most of Mario Party) or Diddy is the second playable Kong in the game.
Now, its possible that Funky Kong and Diddy Kong could make it in Wave 6 but I have my own thoughts on why I think Pauline will get in over Funky. But that's another post for another time.