I think you should really add a reset button that only resets the level and not everything!
The leveling is really fast when the songs are quiet or soft. I don't think anyone would complain if they could kill the monsters on the first few levels real easily, as compared to it's really hard to upgrade because it leveled up too fast.
this may sound stupid but you can't win the professional finals race 2 with a flying type, even at max stats. It's impossible, somehow that stupid fat red bird always wins, can you fix this please? >.>
If career mode is hard (which it isn't), challenge mode should be an impossible badge. namely Challenge 4, which is so annoying especially thanks to the AI.
Weird bug, if I click load game on a new slot, I don't get any achievements rewarded. Plus, there's the menu music and the game music overlapping. good gameplay though. :)