Seviper

In theory, Seviper seems like a functional breaker with its decent mixed attacking stats and movepool. In reality though, it struggles much more than one would think due to lacking bulk, an average Speed tier, and a reliance on Sucker Punch without STAB to hit faster threats, leaving it open to offensive pressure from the likes of Stoutland and Pinsir. It also receives some competition from fellow Poison-types in Skuntank, Haunter, and Victreebel, as they have additional utility such as Defog, Destiny Bond, and Strength Sap, respectively, and they all sport better Speed tiers and a secondary typing.