Crocodilian pokemon have long struggled to find enough food, especially in their most energetic and juvenile stages, and this is only compounded in the case of a pokemon which must literally burn its calories. Fuecoco's appetite is believed to be the reason they went extinct in the wild, and many trainers have marveled at the fact that it ever evolved in the first place. Whatever desert pokemon their ancestors most commonly fed on have long since gone extinct, and only the Bramblin remain as a distant, incorporeal, and quite inedible relic of that species.
It is strongly advised that only travelers train Fuecoco, and not for the usual reason this is advice is given around fire types. Fuecoco have no external flames, and no serious blazes have been sourced to these pokemon. Their ravenous. Guzzlord-like hunger, however, drives them to eat anything they can reach, except for the inside of their own pokeball, so it is best to keep them out in the wilderness when not eating. Fuecoco are common sights at pokemon centers, where nurses often remove a variety of badly charred objects that their digestive systems were ill-equipped to handle.
Struggling trainers often fear the moment of their Fuecoco's evolution, believing they could not afford to feed a Crocalor. Some have even resorted to the use of everstones to prevent it, or reluctantly traded away their newly evolved friends. In all of these cases, the trainers in question made a serious mistake. Fuecoco, like Caterpie, use their juvenile stage to accumulate food for the rest of their lives; their evolved forms are considerably cheaper to care for.