5 species have Guts as a hidden ability, 19 as a normal one

Effect, in PokéAPI's words

“Increases Attack to 1.5× with a major status ailment.”

As a hidden ability

Species	Slot	Note
Flareon	Hidden	Since Generation V
Shinx	Hidden	Since Generation V
Luxio	Hidden	Since Generation V
Luxray	Hidden	Since Generation V
Squawkabilly	Hidden

As a normal ability

Species	Slot	Note
Rattata	Normal
Raticate	Normal
Machop	Normal
Machoke	Normal
Machamp	Normal
Heracross	Normal
Ursaring	Normal
Tyrogue	Normal
Larvitar	Normal
Taillow	Normal
Swellow	Normal
Makuhita	Normal
Hariyama	Normal
Timburr	Normal
Gurdurr	Normal
Conkeldurr	Normal
Throh	Normal
Obstagoon	Normal
Ursaluna	Normal

Elsewhere in PokéAPI

2 more holders without a page here

Alternate forms and other species that PokéAPI lists with Guts.

Machamp Gmax, Squawkabilly Blue Plumage (hidden)