How does the mecanic of daycare work in terms of leveling up?

Question

The Pokemons level up based on how many steps the player does, how many time he spent there or other means?

Answer 1

Pokémon in Day Care gain one experience point per step the player takes.

source

Comments

If you're talking about the daycare in SM/USUM's Paniola Ranch, Pokémon don't level-up while inside the daycare.