The Pokémon daycare South of Goldenrod City
The Pokémon Day Care is a location introduced in the Generation I games where the player can drop off their Pokémon to be taken card by elders and get their levels raised up to a higher level. THis can be an easy way to raise Pokemon.
In Generation I and before obtaining the National Pokédex in Pokémon FireRed and LeafGreen, only one Pokémon can be dropped off at the day care. When obtaining the National Pokédex and defeating the champion Blue, the player can access Sevii Islands Four Island and drop off two Pokémon there. If both are different genders and are in the same Egg Group, they will most likely breed a new Pokémon. On Generation II, onwards, two Pokémon can be dropped off at the day care.
The player is charged free when sending Pokémon to the Day Care, but 
100 to pick them up from the day care and more 100 if they raise up levels. To pick them up, the player must have at least one empty slot in their party for the picked up Pokémon. Each step the player takes equals one additional experience point for the Pokémon at the Day Care.
Trivia
- There is suppose to be a Day Care Trick which can be used to aquire high level Pokemon.