Skadoosh belly attack is an ultimate weapon. Don't let them surround you (agility is a must — prevent roundabout manouvres by dashing same direction) and just push, push, push them to the death. Same tactics works starting from the first enemy to the final boss. I suggest developers to adjust balance of different attack types.
Shop is also nearly useless thing — completing a game without a single purchase is quite comfortable. Don't remember many games where this could happen.
Anyway, had a lot of fun being a beaver, thanks!