If you want to beat the Skull form, I found it best to make sure he's off-screen so you can dodge his attacks without issues, then, with either Loli-pop or Spear, bash him to death every time he starts moving in between attacks. You're welcome.
@bcs5511 no offense dude but you really didnt need to use all those words we wouldve understood you were a smart ass when you said: HA @sixteen. I had no idea? really? cause I thought dime shields were indestructible