I've found a (for me anyway) better way to use your gun's charge attacks. If you switch the lock-on and Devil Trigger buttons and move Fire to RT, you'll always be able to easily charge your guns amidst combos without having to hold down X and fumble to hit B for a grab. I'm a certified idiot so this might not work for you, but thought I'd throw it out there anyway.
Low G Man is the best NES game ever. Disagree and feel the wrath of my spear!