Well these are the ones I personally used
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Trait: Mold Breaker (rivalry also works)
-Superpower/Brick Break/Aqua Tail
With attack rivaling Zekrom's and the ability to out-speed almost every in-game Pokemon after a boost, Haxorus is an absolute monster. DD boosts its great attack and decent speed to awesome levels. The next slot is STAB, and you may decide whther or not you want power or reliability. Then, Earthquake is a needed coverage move allowing Haxorus to reliably hit steel type. With mold breaker, it grants perfect neutral coverage on everything except for Skarmory. The last move provides some more coverage, whether it be fighting or water, with all three options having their benefits and shortcomings.
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Trait: Water absorb (curse body is also fine, but do not use damp)
-Shadow Ball/Ice Beam/Giga Drain/Icy Wind
Jellicent can serve as a wall and double as your means of aquatic transport. Surf has good power and gives you a ride, while will o wisp can neuter physical attackers (except Marhshall's throh and other guts Pokemon). Shadow Ball, Ice Beam Icy Windand Giga Drain can procide additional coverage, with Giga Drain and Icy Wind having useful support side effects. Finally, taunt can be used to hault more support oriented opponents, though the are rather uncommon in game, and Recover may be used if you want to save some money on potions.
Trait: clear body
-Rock Slide/Ice Punch
This guy is one of the best tanks around imo. Base 135 atk, combined with base 130 def and base 90 sp def makes metagross one tough cookie. Metoer Mash is insanely powerful stab, and it has good coverage with Earthquake. Zen Headbutt is nice secondary STAB, while Thunderpunch is nice for bulky water types and the occasional skarmory. Rock Slide can also hit fire types, and Ice Punch helps metagross deal with that ground weakness. Hammer Arm also provides good coverage, and Gross does not care about the speed drop. Stealth Rock can also be run if entry hazards are your thing in game
Well those are just some examples, and there are many more to choose from, but I hope this helps.