(This is about to be a pretty long comment, so fasten your seat belts! TLDR will be at the bottom.)
A good place to start would be to use a Pokémon that resists Ice- and/or Fairy-types, since Goodra is weak to them. Any good Fire- or Steel-type will do for this, so I'd personally recommend either Incineroar or Mega Metagross. As for Goodra's ability, use Sap Sipper Goodra if you choose Incineroar, or Hydration Goodra if you choose Mega Metagross (I'll discuss why below).
If you decide to use Hydration Goodra and Mega Metagross, using Rest on Goodra with Drizzle support is a really good choice. Politoed immediately comes to mind, due to having good bulk, a helpful support movepool, and the Drizzle ability. Not only will Drizzle activate Goodra's Hydration ability, it will negate Mega Metagross' weakness to Fire-types. An EV spread of 244 HP / 36 Def / 20 SpA / 204 SpD / 4 Spe with a Calm nature allows Politoed to survive a Double-Edge from Adamant Mega Kangaskhan, and a Thunder from Modest Life Orb Tapu Koko outside of Electric Terrain... which means you'll need something to overwrite Electric Terrain. Tapu Lele is a great choice here, as Psychic Terrain boosts Mega Metagross' Zen Headbutt and makes a really strong Psychic core.
If you decide to use Sap Sipper Goodra with Incineroar, you should be using Tapu Bulu as well without question. Tapu Bulu's Grassy Terrain halves Earthquake damage, which Incineroar greatly appreciates, and Sap Sipper Goodra won't be affected by any boosted Grass attacks from the opponent. Gengar is a great fit here, since it can also benefit a lot from Grassy Terrain, deal with any opposing Tapus, and is 4x resistant to Poison (which Bulu is 4x weak to). You can either use Mega Gengar for trapping things and finishing them off, or Choice Scarf Gengar to consistently outspeed Tapu Koko and OHKO it with Sludge Bomb.
TLDR: It really depends on what ability your Goodra has.
Hydration: Politoed, Mega Metagross and Tapu Lele.
Never build around a mon like goodra. Make sure goodra supports your core instead
(This is about to be a pretty long comment, so fasten your seat belts! TLDR will be at the bottom.)
A good place to start would be to use a Pokémon that resists Ice- and/or Fairy-types, since Goodra is weak to them. Any good Fire- or Steel-type will do for this, so I'd personally recommend either Incineroar or Mega Metagross. As for Goodra's ability, use Sap Sipper Goodra if you choose Incineroar, or Hydration Goodra if you choose Mega Metagross (I'll discuss why below).
If you decide to use Hydration Goodra and Mega Metagross, using Rest on Goodra with Drizzle support is a really good choice. Politoed immediately comes to mind, due to having good bulk, a helpful support movepool, and the Drizzle ability. Not only will Drizzle activate Goodra's Hydration ability, it will negate Mega Metagross' weakness to Fire-types. An EV spread of 244 HP / 36 Def / 20 SpA / 204 SpD / 4 Spe with a Calm nature allows Politoed to survive a Double-Edge from Adamant Mega Kangaskhan, and a Thunder from Modest Life Orb Tapu Koko outside of Electric Terrain... which means you'll need something to overwrite Electric Terrain. Tapu Lele is a great choice here, as Psychic Terrain boosts Mega Metagross' Zen Headbutt and makes a really strong Psychic core.
If you decide to use Sap Sipper Goodra with Incineroar, you should be using Tapu Bulu as well without question. Tapu Bulu's Grassy Terrain halves Earthquake damage, which Incineroar greatly appreciates, and Sap Sipper Goodra won't be affected by any boosted Grass attacks from the opponent. Gengar is a great fit here, since it can also benefit a lot from Grassy Terrain, deal with any opposing Tapus, and is 4x resistant to Poison (which Bulu is 4x weak to). You can either use Mega Gengar for trapping things and finishing them off, or Choice Scarf Gengar to consistently outspeed Tapu Koko and OHKO it with Sludge Bomb.
TLDR: It really depends on what ability your Goodra has.
Hydration: Politoed, Mega Metagross and Tapu Lele.
Sap Sipper: Incineroar, Tapu Bulu and Gengar.
Hope this helps :)