I'm usually not a fan of flash games... at all... but I was pleasantly surprised by this, this is really well done!
The floating feels a little off, but apart from that, I think you've captured the the feel of the GBA games.
By the way, you might want to know that your moos don't respawn, meaning if you kill one by accident, you're screwed, and losing a life/dying will keep sending you back, and if you dies enough times in a row, you might end up back t the beginning. If you're still alive, still in these forums, and still working on this, than you might want to look into these.