Don't overuse dodges, a lot of attacks will miss if you're just boost-moving around the boss, so save the dodges for stuff that you actually need it for, so you always have EN to spare.

Don't be afraid to burn your EN on flight when warranted, the spinny thing that the Spider does in its final phase is really easy to avoid if you just fly over it.

Don't stop doing damage, consider having something that you can use to at least poke at the enemy just enough to keep the stun bar from decaying, so you can build it up to get a stagger. Or switch to weapons that have a high impact stat to build stagger faster.

Don't sleep on melee weapons. They do MASSIVE damage if you can land the hit.

Pile driver, 2 songbirds and some other high impact you can carry

Open with charged pile driver, immediately unload all your cannons into it, slap another charged pile driver while it's stunned

After that only go for pile driver when it's stunned

I played with reverse joint, but i reckon quad would be the best, as you can just stay above it, outside its melee range.

If it pounces at you while you're on the ground close to it, dive under it