This is for Hatching Eggs
Volcarona and Moltres are the only Pokemon that have this combonation. They learn Fly as an HM and both have the ability Flame Body. Volcarona has Flame Body as a ntural ability, Moltres has Flame Body as a DW ability.
NOTE: Moltres' DW ability is unreleased
Only Volcarona can learn Fly and have Flame Body unless you get Moltres with its special ability Flame Body.
[Pokemon DB Flame Body]
Hope this helps :)