Moves
Leaf Storm is Tangela's main STAB move that allows it to threaten Water- and Ground-types such as Mega Blastoise, Milotic, Gastrodon, and Donphan as well as deliver a huge hit against the likes of Zygarde-10%, Bewear, and Pangoro. Knock Off allows Tangela to remove many relevant items from its opposition, such as defensive Pokemon's Leftovers and offensive threats' Choice items. Leech Seed is very useful for Tangela alongside Knock Off to inflict chip damage on Steel- and Poison-types such as Registeel and Forretress while recovering back its health. Sleep Powder lets Tangela put many relevant threats to sleep that otherwise could be a menace, like Ninetales, Drapion, and Salazzle. Sludge Bomb rounds out Tangela's coverage against many other Grass-types such as Virizion, Mega Abomasnow, and Tsareena and is very useful due to its chance to poison foes. Alternatively, Hidden Power Ice allows Tangela to threaten Noivern and doubles as a safer option to beat Zygarde-10%. However, it leaves Tangela more vulnerable against Virizion. Hidden Power Flying is an option that makes beating Synthesis Virizion way easier and leaves Tangela less vulnerable against the likes of Toxicroak and Emboar.
Set Details
Eviolite boosts Tangela's Defense to great levels while also making its Special Defense a little less bad. Regenerator allows Tangela to repeatedly switch into many threats with safety. 56 EVs in Special Defense and maximum HP investment allows Tangela to take Timid Mega Blastoise's Ice Beam after Stealth Rock, while 92 EVs in Special Attack enable Tangela to OHKO it back with Leaf Storm after Stealth Rock. The rest is dumped into Defense to let Tangela check Zygarde-10% safely. Alternatively, an EV spread of 248 HP / 232 Def / 28 SpD makes Zygarde-10% unable to KO Tangela with Devastating Drake followed by Outrage after one Dragon Dance. The rest is dumped into its Special Defense to help take special hits more easily.
Usage Tips
Knock Off is Tangela's most useful tool and must be used constantly to remove items from its switch-ins and identify potential Z-Move users. Sleep Powder should be used against more threatening Pokemon on the switch, such as Salazzle, Honchkrow, and Noivern, to limit your opponent's options. Due to its access to Regenerator, Tangela can switch into dangerous physical attackers such as Choice Band Tyrantrum and Choice Band Metagross to scout their moves and make switching into them easier. Be aware of Pokemon that can run Toxic to cripple Tangela, such as Donphan and Choice Band Zygarde-10%. Tangela should not stay in on special attackers such as Gardevoir and Raikou because of its bad Special Defense stat. While Leaf Storm is a very powerful STAB move and should be used frequently, be careful about its Special Attack drop, since it can allow opposing Pokemon to set up way more easily against it, such as Virizion and even Zygarde-10%.
Team Options
Tangela can be used to form Fire / Water / Grass cores. Milotic, Slowbro, and Mantine can form defensive cores and offer utility alongside it, while Golisopod and Mega Blastoise offer powerful attacks and entry hazard options. These Water-types can also switch into Fire- and Ice-type moves for Tangela. On the other hand, Arcanine, Salazzle, Ninetales, and Houndoom complement the core's offensive presence and appreciate Tangela's ability to switch into Water-, Rock-, and Ground-type attacks. Rock-types such as Rhyperior, Tyrantrum, and Lycanroc-D greatly benefit from Tangela's ability to lure in Fire-, Flying- and Poison-types, which allows them to set up Stealth Rock or fire off powerful attacks. Steel-types like Registeel, Bronzong, Metagross, and Escavalier can switch into Ice-type moves that threaten Tangela and are also immune to Toxic. On the other hand, Tangela offers a useful Ground-type resistance and can pivot into many Fighting-types. Florges, Mantine, and Goodra can make Tangela's life easier against special attackers like Mega Blastoise, Ninetales, and Roserade. Additionally, Florges is able to offer cleric support to remove status from Tangela, and the former two can also remove hazards from the field.