Overgrow
Strengthens Grass moves to inflict 1.5× damage at 1/3 max HP or less.
Full effect
When this Pokémon has 1/3 or less of its HP remaining, its Grass-type moves inflict 1.5× as much regular damage.
In game description
Powers up Grass-type moves when the Pokémon's HP is low.
Pokemon with Overgrow
#0001
Bulbasaur
#0002
Ivysaur
#0003
Venusaur
#0152
Chikorita
#0153
Bayleef
#0154
Meganium
#0252
Treecko
#0253
Grovyle
#0254
Sceptile
#0387
Turtwig
#0388
Grotle
#0389
Torterra
#0495
Snivy
#0496
Servine
#0497
Serperior
#0511
Pansage
hidden
#0512
Simisage
hidden
#0650
Chespin
#0651
Quilladin
#0652
Chesnaught
#0722
Rowlet
#0723
Dartrix
#0724
Decidueye
#0810
Grookey
#0811
Thwackey
#0812
Rillaboom
#0906
Sprigatito
#0907
Floragato
#0908
Meowscarada
Bulbasaur
#0002
Ivysaur
#0003
Venusaur
#0152
Chikorita
#0153
Bayleef
#0154
Meganium
#0252
Treecko
#0253
Grovyle
#0254
Sceptile
#0387
Turtwig
#0388
Grotle
#0389
Torterra
#0495
Snivy
#0496
Servine
#0497
Serperior
#0511
Pansage
hidden
#0512
Simisage
hidden
#0650
Chespin
#0651
Quilladin
#0652
Chesnaught
#0722
Rowlet
#0723
Dartrix
#0724
Decidueye
#0810
Grookey
#0811
Thwackey
#0812
Rillaboom
#0906
Sprigatito
#0907
Floragato
#0908
Meowscarada
Using Overgrow in Cobblemon
Abilities are passive and always active, so Overgrow costs you nothing to run. If it is marked hidden on a species above, expect it to be harder to obtain: servers differ in whether hidden abilities come from breeding, an Ability Patch, or events.
See the Pokedex for which abilities each species can have, and IVs, EVs and breeding for how to actually pass one down.