Swellow

Swellow has not changed much throughout the passing generations, as its true potential has always rested in its ability, Guts. When Guts is activated, Swellow can clean up weakened teams, and being one of the fastest Pokemon in NU makes it difficult for it to be outsped. However, Swellow is very easy to stop, as its lack of coverage and low bulk make it an easy target. Swellow's Stealth Rock weakness and its vulnerability to priority attacks also make it increasingly difficult to use; even though it packs a punch, a lot of Pokemon can tank Swellow and KO it in retaliation. Additionally, the combination of Toxic Orb's effect, Brave Bird, and its frailness allow it to be easily worn down. Also, Swellow has difficulty defeating many Rock- and Steel-types in the tier alone, so it often relies on team support to get past them.