Check Supreme Ninja's comment for strats too. I'm not sure if pulse really is the best weapon, but I took it and it worked. If you want an easy way to beat the boss, do the following:
For missiles, move in a large U shape around the sides and bottom of the screen. The initial missiles will despawn as you move side to side, giving you plenty of space to maneuver and hit the boss.
For the pulse lasers, just go to either side of the screen and sit there :)
V-Shaped+Normal Shots, go to the right side of the screen at the very bottom. You can absorb one shot and go between the V’s. Between each "layer" of shots, you can move back to the middle to hit the boss a bunch
For criss-cross, holy hell good luck. The right side seems to be good, but since the shots move, you'll have to tank a few to move to other locations.
The boss’s rotation of weapons is RNG, so it can get harder or easier. There’s also a small interval between each rotation of weapons that you can go and hit the boss for free.
Honestly, having a person with missile +1, missile bounce +2 dmg, and missile knockback, using a simple greasy oil is so op. no need to wait for energy, just 7 dmg chunks each time, and since it only costs 3, you're gaining energy!
 "Reactance"){kind=icon}
 "The Last Stand"){kind=icon}
 "Deadly Neighbours"){kind=icon}
 "Exit/Corners"){kind=icon}