Qwilfish, the Balloon Pokémon. The quills covering the entire body have evolved from scales. A Qwilfish can cause its body to swell in order to shoot its needles in all directions.
– Ash’s Pokedex
Qwilfish seems like a filler Pokemon. It’s the Water/Poison type that’s not Tentacool/Tentacruel. And I often forget about it because it has no evolutionary families or related Pokemon, and it’s not especially outstanding in any way.
Stat-wise, it has good Attack and Speed, though one of its abilities is Swift Swim, which can actually make it quite fast actually. Its defenses are pretty low, but it can learn Stockpile that can help boost it.