Yamimon
I beat Kirby: Return to Dreamland 100%! And I find that the Leaf Ability is the best. You can hide as a bush by pressing A and you don't even get hurt at all! I basically survived the True Arena by doing that. That and I had friends helping me. But at the odd time I had to defeat a boss on my own, like Fatty Puffer EX, Goriath EX, HR-D3... it wasn't easy hiding, deciding when to attack, when to hide... but we managed to do it in around... 40 minutes.
That kinda reminds me of using the rock ability in the True Arena of KSSU. Took me 21 minutes, then I redid it with hammer and beat it in 8.
For me, I have the most luck in the arenas with tornado, which I used to beat both of them. The leaf ability for me was just too weak for my taste (in the arenas. I love it in adventure mode). I like being able to beat bosses in the arenas with only a few attacks (like using Bugzy in Helper to Hero, you can beat a lot of the bosses with one blow)