Rate my Ultra Sun Team for Double Battle Tree

Question

Hippowdon EVs: 248 Hp / 252 Atk / 8 Sp.Def
Nature: Careful
Ability: Sand Stream
Item: Red Card

-Stealth Rock
-Fire Fang (Coverage Ice And Grass Weakness)
-Earthquake (Covers Aggron Fire Weakness and STAB)
-Slack Off

Mega Aggron EVs: 248 Hp / 252 Atk / 8 Sp.Def
Nature: Careful
Ability: Filter
Item: Aggronite

-Iron Head (STAB)
-Magnet Rise (Prevents Ground Weakness)
-Thunder Punch (Coverage for Hippowdon Water Weakness)
-Aerial Ace (Coverage Fighting Weakness)

Alolan Muk EVs: 248 Atk / 252 Def / 8 Hp
Nature: Impish
Ability: Poison Touch
Item: Sitrus Berry

-Gunk Shot (STAB)
-Ice Punch (Coverage Ground Weakness And Wishiwashi Grass Weakness)
-Acid Armor
-Recycle

Wishiwashi EVs: 252 Def / 252 Sp.Def / 4 Sp.Atk
Nature: Bold
Ability: Schooling
Item: Leftovers

-Helping Hand
-Toxic
-Protect
-Scald (STAB)

I'm actually quite new to competitive team building, but i am open to suggestions and opinions. Only thing is i would like to work around an Alolan Muk Physical Sweeper as i am a Poison type lover. Thanks in Advance for helping me out!

Comments

This will probably help more than a team rate. https://docs.google.com/document/d/1qYztMbBTY0qm4mFy1-66bafgsVQ2gkeErAO3QUghEBY/edit?usp=sharing
In case you're wondering, the best poison Pokemon in Battle Tree doubles is Amoongus.

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Thanks a lot for the guide you provided, also thanks for letting me know which poison type fits best in double battles format as it is the primary format I'm actually enjoying the most.

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You have no Psychic coverage...