I propose an upgrade to the Pulsar's charge attack that, in the spirit of the Roarmulus twins (who need to be defeated in order to get the gun), fires a giant laser that pierces enemies instead of a "powered up" normal bullet.
This attack would function much like the Autogun's, rooting the player in place for about the same amount of time, but would affect a smaller area width-wise and deal slight knockback in the direction of the beam.