Smelt is a move skill that can be used by any Pokémon that knows the move Incinerate, Inferno, Ember, Burn Up, or Blue Flare. This move gives power to a furnace, as if it has been powered by coal or another burnable item. The length that the smelting power lasts depends on which move is used.
For the stronger Fire-type moves, a number of items in the furnace will instantly smelt.
Smelt's cooldown timer is 2 minutes for all moves but Ember, which has a cooldown of 1 minute.