Plunket is different of course. And it seems that your playstyle is different from what one would expect. If you use it the same way you use the Plunket, you won’t run into problems.
Though I question the choice of the machine with that kind of playstyle: its strong point is a continuous fire bonus… Not really the playstyle to take advantage of it. You’d be better off with a regular Droog.
Most Nisha players are much more frantic.
I once made a list of all the bosses in the game, and between Corrosive and Shock, you can match element on over 80% of them.
rk-5, Felicity, Eclipse, Eos, Despair and Self-Loathing, Opah superior, Flameknuckle, The other Felicity from the dome and Shadowtrap… All are weak to Corrosive.
A sizeable portion of all bosses have shields and some of them are over 70% shield: Deadlift is almost all shield, Bosun has one, Denial subroutine too, The sentinel effectively has 4 shield bars for just one health bar, Eos has 3 shield bars for one health bar.
A small minority of bosses will resist part of these 2 elements: Iwajira is pure flesh, Bosun is half flesh, Denial subroutine is also half flesh… That’s pretty much it. 2 of these 3 are in a vacuum making fire less interesting once again.
In short, in TPS, it’s shock and Corrosive against bosses and neutral elements for mobbing (NE, explosive, Cryo, shock… Whichever you prefer)