Swoobat

Thanks to Simple, after a single use of Calm Mind, Swoobat's Special Attack reaches threatening levels. Also in Swoobat's favor is its access to Stored Power, a STAB attack that works well in conjunction with Calm Mind, becoming pretty powerful after just one use of the latter, and its Base Power can further increase should Swoobat acquire a boost from whichever Berry you choose to run. Even before a Salac Berry boost, Swoobat outspeeds the majority of the unboosted metagame. However, it needs a boost to inflict any significant damage, and Stored Power is pathetically weak off the bat. It also has limited setup opportunities because of its horrible bulk. Furthermore, it struggles against stall teams, as a mediocre Special Attack stat means that Swoobat requires multiple boosts to get past walls like Audino. Additionally, Swoobat is beaten by common threats such as Pawniard and sports a Stealth Rock weakness. To top it all off, it is vulnerable to priority and prone to being revenge killed if it isn't behind a Substitute, though a Kee Berry can somewhat mitigate this.