I don't know if this counts as a glitch, but if you switch left and right quickly, you can do fast damage with charged Aiming Laser, with maximum 4 hits every 7 frames.
This is a demonstration TAS of Generaid Core (mid-boss of Storm Owl's stage) and Tentoroid (mid-boss of Split Mushroom's stage). Other bosses are all immune to Aiming Laser, so I can't perform this anywhere else.