For those who need help...
Wave 1: Let the adds kill themselves in the first part by running around them. After the boss appears rinse and repeat. When the boss is the last one standing, melee him to death, or trick it into "yarning" itself. Not too hard...just don't waste bombs for this wave.
Wave 2: Pick off the adds one by one. Their buzz saw attack cannot be stopped by melee swings but has a limited horizontal range. After the boss has joined the fray, run up and down the screen until the boss begins to "fish". If possible, damage the adds until the boss is exhausted, and thus exposed to attacks.
Wave 3: Keep your distance from the adds, since they have fast swings. It's best to bomb them from a distance or let them keyframe each other to death. Once one of them has fallen, divide and conquer! When the boss arrives, run around until he fires rockets or bait him to punch/bodyslam the adds. Avoid attacking the boss from the sides, since that will trigger his attacks.
Wave 4: The adds have a long reach and a nasty blam attack. After they blam, they'll be vulnerable to attack. You'll first face a pair of adds and then a trio. When the bosses emerge, avoid them until one becomes airborne. While avoiding the bubbles, take down the ground guy first by attacking and backing off (he'll attack as soon as he gets up). When he dies, jump swing at the floating guy until he comes down. Keep attacking him until he dies (while watching out for his spin attack too).
Final Boss: Avoid the adds at all costs, since they instantly attack when you're close. The boss teleports around the room and fires a...lazer...which is a slow death if you get hit (assumming you have low heath of course). Don't bother with the adds since they keep respawning. Other then that, good luck.