I have a whole party full of Pokémon with the Flame Body Ability, but it still takes a while for the Eggs to hatch. Why is this, I was under the impression Flame Body stacked when hatching an Egg, is this not the case?
Flame Body and Magma Armor do not stack if you have multiple of those Pokémon in your party. Sorry :( This is why your egg hatching still takes the same amount of steps: half of what it should be.
However, this effect will not stack up if multiple Pokémon with Flame Body and Magma Armor are in the party
Bulbapedia
no is does not work if that was the case then your eggs would hatch every step. nintendo designed it this way so it wouldnt happen. try using hatching power located luminose city.
sorry, no. it only works if the egg is in first slot (i think) and the flame body Pokemon is in second. Because of this, you cannot hatch any faster or it would be over powered (32x faster).
Hope I helped.