8 species have Harvest as a hidden ability

Effect, in PokéAPI's words

“Has a 50% chance of restoring a used Berry after each turn if the Pokémon has held no items in the meantime.”

As a hidden ability

Species	Slot	Note
Exeggcute	Hidden	Since Generation V
Exeggutor	Hidden	Since Generation V
Tropius	Hidden	Since Generation V
Phantump	Hidden
Trevenant	Hidden
Smoliv	Hidden
Dolliv	Hidden
Arboliva	Hidden

Elsewhere in PokéAPI

1 more holder without a page here

Alternate forms and other species that PokéAPI lists with Harvest.

Exeggutor Alola (hidden)