I'm going to have to side with TehEpicRyuga and her friends. Kirby is a pretty big Nintendo franchise, and calling it small, insignificant, or undeserving is pretty silly, in my opinion, especially given it's unique gameplay, wide variety of original spinoffs, and colorful cast of characters. Bandana Dee is also one of the main 4 Kirby characters now, and the Kirby series doesn't feel complete without him there. I'd love to see Bandana Dee join the battle!
Also, the whole notion of setting number of series' reps based solely on sales is absolutely ridiculous. As a long as a character can bring something new and interesting to the roster, they should be seriously considered before being ruled out, regardless of their series's number of reps. Now, yes, sale should play some role is selecting characters, but it should be minimal. Fire Emblem, for example, is extremely well-known throughout the world by this point, and characters like Robin and Lucina bring a completely new type of playstyle to the cast and fill a particular niche, respectively. While Fire Emblem's not the biggest seller for Nintendo, it's so well-known and the characters are unique enough that the reps definitely deserved their spots. The same goes for Ridley, Bandana Dee, Pichu and any other character in a similar situation. Sales should never, ever be the sole factor in determining how many reps a series should get.