Snorlax, properly trained, are an enormously powerful pokemon, commonly seen at the highest levels of Pokemon League competition. However, they are curiously rare in the lower levels, unlike others such as Garchomp or Metagross who are similarly known for their power. This is not solely because Snorlax quickly rise to the top of their respective competitions, although this does play a role: it is also because the expense of feeding a Snorlax soon renders them unaffordable for lower-level trainers.
In the wild, where they sleep for a month at a time, a Snorlax's appetite when it wakes can devastate the surrounding area. Trained Snorlax still sleep often, but they must also train and battle, which burns more energy. These Snorlax must eat even more than the usual 800 pounds of food a day to maintain the thick fat which makes them so difficult to take down in combat.
Trainers deal with this issue in a variety of ways. Some take out significant loans and battle frequently, hoping that the prize money from success will eventually cancel out the cost of upkeep.. Others treat their Snorlax like its wild counterparts, waking them only for tournaments with prize money on the line to lower their metabolism and stave off bankruptcy. A few are forced into underfeeding them, and their Snorlax are relatively lean, but this makes them weaker in combat, for a lean Snorlax is as sluggish as a fat one but less able to take a hit. And sadly, far too many are forced to say goodbye and release them back into the wilderness, after a long search for somewhere with enough food for them to prosper.