The Pokémon Day Care Center is a facility where Trainers can leave their Pokémon to let it gain Experience Points depending on how long one leaves it there. This can be an easy way to raise Pokémon and breed.
In Generation I, prior to obtaining the National Pokédex in Pokémon FireRed and LeafGreen, only one Pokémon can be dropped off at the Day Care. After obtaining the National Pokédex and defeating the Champion Blue, the player can access the Sevii Islands and at Four Island there is a facility in which he/she can store their Pokémon. If both are different genders and are in the same Egg Group, they will most likely breed a new Pokémon. In Generation II, onwards, two Pokémon can be dropped off at the day care.
Run by the Day Care Couple, the Trainer will be charged a price of 100 per level increase of a single Pokémon. In Generation IV, the Day Care Center was upgraded with a Pokétch peripheral which allowed the Trainer to view their Pokémon's progress, through the use of a Day-Care Checker. When deposited in the Day Care Center, Pokémon are taught moves by the Day Care Couple according to level.
In the Manga
In the Gold, Silver and Crystal Chapter of the Pokémon Adventures manga, there is a Pokémon Day Care located in the Johto region. This is where Gold travels to in order to strengthen his Pokémon to defeat Silver. During his training, the Day Care Couple "trained" Gold by facing him off with a multitude of Pokémon, resulting in his Exbo evolving into a Quilava.
- There is supposed to be a Day Care Trick in which the Trainer can acquire high level Pokémon.