0211 Qwilfish

Water Gun performs way better than Poison Sting, which is one of the worse fast moves in PvP. 

Aqua Tail sees frequent use on Qwilfish, being the most spammable charge move and allows Qwilfish to bait shields and apply shield pressure or decent STAB damage.

The choice between the remaining charge move options is up to preference, and varies depending on your strategies and playstyles. Acid Spray costs 5 less energy than Ice Beam and is guaranteed to apply a debuff on an opponent, but the latter provides good coverage. Sludge Wave can deal big STAB Poison-type damage if unshielded, but a relatively high energy cost of 65 makes it less preferable due to unspectacular energy gains from Water Gun (3.0 Energy Per Turn) and the lower bulk of Qwilfish.

The introduction of the TSR Twilight Cup back in February 2019 brought some attention and spotlight to Qwilfish, which became notable for being a relatively safe lead and spammer of Aqua Tails. Outside of that cup however, Qwilfish sees much less use due to relatively low bulk compared to other options. Its moveset also isn't anything spectacular either, which prevents Qwilfish from distinguishing itself from its competitors. One interesting niche going for Qwilfish is that it doesn't have a vulnerability to Grass-type attacks, which has been an issue with other popular Water-type picks such as Azumaril, Lapras, and Lanturn. A total of 8 resistances gives Qwilfish an advantage in those particular fights, but there's more to be desired if Qwilfish is to rise to the top of the ranks.  

With a max CP of 2051 and low bulk, Qwilfish is mostly puff and no stuff in Ultra League. However, its Poison-typing and charge moves does give it a niche against Fairy-types.

It huffed, and it puffed, and it got blown away.