They’re fixed but can change depending on the angle/camera direction with some skills. With HE’s charge the one ahead of you is based on where you’re facing (so you can change where that strike goes) unless you ram a wall in which it’s always fixed to be directly ahead.
Ball shot rotates based on what direction you’re facing when you fire it from what I’ve noticed while playing
Ball slam is always just a ring that forms around the explosion at random strikes
Sea beast’s explosions only happen if you have water beam impacting a solid surface, water sharks chase down players so it can be randomized, water walls and whirlwind are fixed
Hell’s double slam is fixed and so is Thunderflame gun, which will explode regardless of what it’s shooting at