I'm having some trouble where I frequently get knocked back in bounds when i get skewed by the 2nd set of bats (unbuffered). What i want to know is what I can do to stop that from happening? Do I need to hold the c-stick down for a longer or shorter amount of time? Or maybe hit the c-stick sooner or later than i am? Any help is appreciated.(Also I can provide a video of it happening if that would help)

If you're getting knocked in bounds you're not holding the C-Stick down long enough. If the skew is too good, then Luigi can't maintain the angle while out of bounds and he gets pushed back in bounds. If you don't hold the C-Stick long enough, then the skew won't be good enough. Just experiment around with it, and try holding it a little longer, since you keep clipping back in bounds. Happy learning!