A poffin raises the Pokemon's condition. Depending on what flavor it is, it'll raise a certain contest stat (Beauty, Cuteness, etc.), much like Pokeblocks (but with tate rather than color). The higher your condition, the more points you get in the first round (when you show off your Pokemon before the appeal rounds). They also raise friendship, so you could feed them to Pokemon that require friendship to evolve (Golbat, Eevee, etc.)
Dry Poffins increase Beauty
Spicy Poffins increase Coolness
Bitter Poffins increase Smartness
Sour Poffins increase Toughness
Sweet Poffins increase Cuteness
