yea, I'd keep waterfall since it's stab and has a decent amount of supereffective and neutral coverage.
Curse would be nice if you can set it up, just keep in mind that skarms can whirlwind you out, and better yet, be able to take a hit if you're 1x cursed. Hazers, too.
I think penguin pal has a good idea going:
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Trait: Torrent
Nature: Adamant / Impish
EVs: 252 HP / 172 Attack / 80 Defense
- Waterfall
- Earthquake
- Stone Edge / Icebeam
- Curse / Rest
you'll definitely want the stab move, and then another move to cover what's resistant to water... don't do the speed down nature since you have a chance of being faster than pokes like snorlax, which is nice if both of you are setting up curse.
you don't want to depend too much on torrent... if it activates after you've put a couple curses down, a special move can still destroy you, and can be guaranteed first hit since you've lost out on speed.