4 species have Skill Link as a hidden ability, 5 as a normal one

Effect, in PokéAPI's words

“Extends two-to-five-hit moves and Triple Kick to their full length every time.”

As a hidden ability

Species	Slot	Note
Aipom	Hidden	Since Generation V
Ambipom	Hidden	Since Generation V
Minccino	Hidden
Cinccino	Hidden

As a normal ability

Species	Slot	Note
Shellder	Normal	Since Generation IV
Cloyster	Normal	Since Generation IV
Pikipek	Normal
Trumbeak	Normal
Toucannon	Normal

Elsewhere in PokéAPI

1 more holder without a page here

Alternate forms and other species that PokéAPI lists with Skill Link.

Heracross Mega