World 2 Boss strategy
You can keep Spike but EE-Lectric is much more useful since he can shoot electricity balls. Collect the EE-Lectric costume and level him up, then face the Boss. Fire electricity at him a few times while targeting (hold X and use the D-pad to move) so you can hit him. You can eventually press Y before he does. Execute a special move by pressing R+ X or Y to kill him.