Well, koff~
I kind of modified my challenge a tad. Originally, I was going to go with the Shinobi ability in Kirby Superstar Ultra, but I decided to forgo the Ninja Ability in favor of the Yo-Yo ability instead, seeing as how it's more readily available in more of the games. I maintain that I have not used any power other than the Yo-Yo to defeat enemies and bosses. Other than that, yeah.
I did start Squeak Squad up and going through the game Using the BEAST ability. Just kidding, but not really. I've been using the Animal ability. I'm going through some of these levels and it seems like they just kind of skimped in some areas. I'm passed stage 4, and the crab-mech gave me the most trouble due to the short range the Animal ability has. Other than that I'm good, koffi~