Poffins are made from Berries. The flavor of the berry determines the flavor of the Poffin. You are able to make Poffins at the Poffin House in Hearthome City. However, you must obtain the Poffin Case from the Pokémon Fan Club chairman, also in Hearthome City, in order to do so.
Poffin levels can be found with this formula:
B is the base level
T is the time taken in seconds
b is the number of burns
s is the number of spills
Likes or dislikes
Depending on a Pokémon's nature, they might prefer Sour poffins, Sweet Poffins, etc. These are the second coming of PokéBlocks from R/S/E. Beware if it overflows or burns because it will worsen the poffin's flavor and the Pokémon may dislike it, unless if it eats anything happily. The faster you finish the poffin, the bigger the flavor of the poffin and it might even become a Mild Poffin. To get a free one, talk to a Rich Guy in Hearthrome City in the front of the counter and he will give you a Mild Poffin and steps aside and lets you enter a contest. You don't have to always enter the contest although.