Flame Body
Has a 30% chance of burning attacking Pokémon on contact.
Full effect
Whenever a move makes contact with this Pokémon, the move's user has a 30% chance of being burned. Overworld: If any Pokémon in the party has this ability, each egg in the party has its hatch counter decreased by 2 (rather than 1) each step cycle, making eggs hatch roughly twice as quickly. This effect does not stack if multiple Pokémon have this ability or Magma Armor.
In game description
Contact with the Pokémon may burn the attacker.
Pokemon with Flame Body
Ponyta
hidden
#0078
Rapidash
hidden
#0126
Magmar
#0146
Moltres
hidden
#0218
Slugma
#0219
Magcargo
#0240
Magby
#0467
Magmortar
#0485
Heatran
hidden
#0607
Litwick
#0608
Lampent
#0609
Chandelure
#0636
Larvesta
#0637
Volcarona
#0662
Fletchinder
#0663
Talonflame
#0838
Carkol
#0839
Coalossal
#0850
Sizzlipede
hidden
#0851
Centiskorch
hidden
#0935
Charcadet
hidden
Using Flame Body in Cobblemon
Abilities are passive and always active, so Flame Body 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.