By far the most annoying part of this level, possibly the game, is the Naga vs. 3 mechatanks portion. Besides the tutorial parts (which might be required for Jill of All Trades), I suggest forgetting about the jump button.
You should be spamming fire
whenever possible and swiping with the bumpers
when they are close and fire's not available. You can hit them from one lane over with the correct bumper, so don't worry about needing to stay in front of them.
Whenever you have a spare moment, put up your water shield
just in case.
When they back up and start raising rocks, just keep blasting. Jump only if you've run out of fire. When they charge forward, obviously duck to the side.
When they are in close and pull back to punch, just be safe and both
and move over. DON'T JUMP. The telegraphing is TERRIBLE, so just assume you have to both slide and move and you'll be good. Once I figured that out, I beat it the next go-around.