Swampert

Mega Swampert is a physical rain sweeper with high Attack, a well-rounded movepool, respectable bulk, and only one weakness. Whereas other rain sweepers like Kingdra and Ludicolo offer fast but frail stat spreads that are suitable for highly offensive teams, Mega Swampert has enough bulk and power to function well on bulkier, more balance-oriented teams that still want the speed advantages offered by a Swift Swim user. Unlike other popular rain sweepers, Mega Swampert isn't able to make use of an item to augment its power, but its base Attack stat is significantly higher to compensate. That said, as a physical attacker, Mega Swampert can quickly be shut down by Intimidate users like Mega Salamence and Scrafty. Thanks to Mega Evolution mechanics, Swampert is always guaranteed a Swift Swim Speed boost on the turn it Mega Evolves if a rain setter is switched in on that turn, making it a much more flexible and forgiving lead than other Swift Swim users. However, Mega Swampert also takes up a team's Mega slot, whereas its alternatives do not. Furthermore, while Mega Swampert's movepool offers more well-rounded coverage than Kingdra's and Ludicolo's, it still has a slight case of four move-slot syndrome; it really wants to run Waterfall, Earthquake, Ice Punch, and Superpower on the same set but needs to give up one of those moves for Protect.