4 species have Storm Drain as a hidden ability, 4 as a normal one

Effect, in PokéAPI's words

“Redirects single-target Water moves to this Pokémon where possible. Absorbs Water moves, raising Special Attack one stage.”

As a hidden ability

Species	Slot	Note
Lileep	Hidden	Since Generation V
Cradily	Hidden	Since Generation V
Maractus	Hidden
Tatsugiri	Hidden

As a normal ability

Species	Slot	Note
Shellos	Normal
Gastrodon	Normal
Finneon	Normal
Lumineon	Normal

Elsewhere in PokéAPI

2 more holders without a page here

Alternate forms and other species that PokéAPI lists with Storm Drain.

Tatsugiri Droopy (hidden), Tatsugiri Stretchy (hidden)