Welcome to Smogon! Take a moment to read the Introduction to Smogon for a run-down on everything Smogon, and make sure you take some time to read the global rules.
You deal (16 + 40.5 + 16) 72.5 Damage this way! The Earthquake + Counter does a lot more damage than the straight Endeavor on A2 (which only does 38.stuff). This puts Gallade at 26 HP for Nidhogg's mauling pleasure, not counting whatever damage Poseidon deals on the way out.
TLR's an exclusive RP, so Slowking's out of the question...That, & deadfox has apparently agreed to come along with me on IRC...Sorry mate. If Slowking wasn't in TLR/TLR wasn't an exclusive RP, I may have considered you.