Mantine serves a niche in checking many offensive Water-types such as Ash-Greninja, Manaphy, and Mega Swampert, which are commonly seen on rain teams. It can also check other offensive presences such as Heatran, Kommo-o, and Mega Charizard Y, making Mantine a solid defensive option on certain teams. However, it tends to be shaky defensively because it's easy to overwhelm, forcing it to constantly use Roost, as well as being incredibly weak to Knock Off. Haze lets Mantine comfortably check Manaphy and Volcarona by negating their setup. Meanwhile, Toxic allows it to punish switch-ins like Slowking, Tangrowth, and Hydreigon. Defog is another option, but since Mantine loses to or gets crippled by many Stealth Rock setters in the tier such as Garchomp, Clefable, and Mega Tyranitar, it is generally not a good sole Defogger. A specially defensive spread is used so Mantine checks special threats such as Heatran, Ash-Greninja, and Volcarona. Water Absorb allows Mantine to safely switch into Water-type moves from the likes of Urshifu-R, Ash-Greninja, and Manaphy.
Due to its resilience against Water-types, Mantine is a great defensive backbone for teams that feature a wincon that struggles against Water-type Pokemon, so the likes of Gliscor, Volcarona, and Excadrill make for excellent teammates, often luring in Water-types like Urshifu-R, Mega Swampert, and Ash-Greninja. Due to Mantine's crippling weakness to Electric-types, it appreciates partners that are able to handle the likes of Zeraora, Tapu Koko, and Magnezone. Therefore, pairing it up with Gliscor, Ferrothorn, or Landorus-T makes for a solid defensive core. It's also susceptible to Rock-types such as Mega Tyranitar and Mega Diancie, so it appreciates teammates such as Hippowdon, Gastrodon, and Ferrothorn, which are able to switch into their attacks. Meanwhile, Mantine checks Fire- and Water-types for them in return. Its weakness to Knock Off means it likes Pokemon that don't mind taking Knock Off such as Mega Scizor, Gliscor, and Z-Move variants of Hydreigon and Heatran. Due to Mantine's amazing matchup against rain teams, Pokemon that struggle with rain such as Landorus-T, Excadrill, Tyranitar, and Heatran appreciate having it to fall back on defensively in this matchup.