XL Candy is a resource in Pokemon Go that allows players to level up their Pokemon beyond the original Level 40 cap, all the way to Level 50. It is a Pokemon-specific Candy that can only be fed to that particular species of Pokemon. XL Candy is much rarer than regular Candy, and there are several ways to obtain it, including catching Pokemon, transferring Pokemon, hatching eggs, trading Pokemon, walking buddies, and converting regular Candy into XL Candy. The quickest way to get XL Candy is to catch Pokemon, as players have a chance of receiving 1-3 XL Candy per catch. However, it wont happen every time, and the amount of XL Candy received varies depending on the species of Pokemon. For example, catching evolved, Legendary, or Mythical Pokemon guarantees players at least 2 XL Candy for evolved creatures, and a minimum of 3 XL Candy for Legendary and Mythical Pokemon.

In summary, XL Candy is a rare resource in Pokemon Go that allows players to level up their Pokemon beyond Level 40. It is Pokemon-specific Candy that can be obtained through various methods, including catching Pokemon, transferring Pokemon, hatching eggs, trading Pokemon, walking buddies, and converting regular Candy into XL Candy.