11 species have Gluttony as a hidden ability, 16 as a normal one

Effect, in PokéAPI's words

“Makes the Pokémon eat any held Berry triggered by low HP below 1/2 its max HP.”

As a hidden ability

Species	Slot	Note
Bellsprout	Hidden	Since Generation V
Weepinbell	Hidden	Since Generation V
Victreebel	Hidden	Since Generation V
Snorlax	Hidden	Since Generation V
Gulpin	Hidden	Since Generation V
Swalot	Hidden	Since Generation V
Spoink	Hidden	Since Generation V
Grumpig	Hidden	Since Generation V
Munchlax	Hidden	Since Generation V
Skwovet	Hidden
Greedent	Hidden

As a normal ability

Species	Slot	Note
Shuckle	Normal
Zigzagoon	Normal
Linoone	Normal
Pansage	Normal
Simisage	Normal
Pansear	Normal
Simisear	Normal
Panpour	Normal
Simipour	Normal
Heatmor	Normal
Applin	Normal
Flapple	Normal
Appletun	Normal
Lechonk	Normal
Oinkologne	Normal
Dipplin	Normal

Elsewhere in PokéAPI

12 more holders without a page here

Alternate forms and other species that PokéAPI lists with Gluttony.

Rattata Alola, Raticate Alola, Raticate Totem Alola, Grimer Alola, Muk Alola, Slowpoke Galar, Zigzagoon Galar, Linoone Galar, Snorlax Gmax (hidden), Flapple Gmax, Appletun Gmax, Oinkologne Female