Swampert

Swampert commonly sees use as a rain attacker that can support its team well with its ability to threaten fast and frail foes with powerful attacks. Solid defenses and an immunity to Electric make Mega Swampert a strong, bulky, and fast threat under the rain that is difficult to defensively check and swiftly take out. Apart from being a sweeper under rain support, Swampert can opt to stay in its regular forme and act as a bulky support Pokemon, using moves like Stealth Rock, Roar, and Yawn while retaining a different kind of offensive presence when compared to other leads.

Though Mega Swampert's offensive prowess under rain cannot be overlooked, it is dependent on the rain to function due to its relatively low Speed in other weather conditions. This leaves Mega Swampert with a rigid and limited pool of Pokemon that it can synergize with. Mega Swampert can 2HKO many neutral targets with its STAB moves, but there are many Pokemon that can be used to pivot around Mega Swampert's STAB moves until the rain stops. Some Pokemon can switch into a resisted Waterfall, and other common Pokemon like Landorus-T and Mega Salamence can switch into Earthquake and weaken Mega Swampert in an emergency. This means there will be difficulty for Mega Swampert to function well as an offensive Pokemon even in rain. Mega Swampert also may compete with Kingdra as a Swift Swim sweeper, as Kingdra does not take a Mega slot, can hold an item of its choice, and sports a secondary typing that situationally has better coverage; however, Kingdra struggles against foes like Toxapex, Tapu Fini, and Mimikyu that Mega Swampert fares better against.