Darky Dee
Smash Journeyman
The fact that she is still there is a lot to say for itself though, also the fact that she was the star in DK3. She is part of the original cast before it got blown out of proportion with all the Kongs in DK64.Dixie's been in Mario Spin Offs. That's all she really has going for her over K. Rool besides being a playable character. K. Rool is still actually important in the games he appears in though, Dixie not having had a role besides as a generic extra character since DKC3.
Has Waluigi had his own title and been playable in more than just one game that is canon to the series' story? (I am aware that Mario's stories never really follow one another, but I don't ever remember him being playable in any Super Mario games, and I still consider him a "Super Mario" character than a "WarioWare" one at that since he got ditched by that series, which goes to prove how unimportant he is.)So if we go by that logic, Waluigi is more likely then Bowser Jr. due to having been playable more often and having been in spin-offs, despite him having no role whatsoever. Spin Offs mean nothing, do you want to see Waluigi playable?
If I remember correctly, X-Play even dubbed him as a WTF character in the Mario series. But back to the main point, Dixie Kong has a lot going for her compared to Bowser Jr. and Waluigi.
Sorry for editing-- I don't like double-posting if that's a problem.