How does the EXP gain works in the Daycare?

Grinding takes a while and I hate grinding Bug Pokémon, so they're weak :disgust:

So anyway, I was wondering what would be faster to get some Lv40 Pokémon to Lv50, grinding or daycare raising?

In order to get an answer to this question, I need to know how the daycare raising works. Do the monsters gain 1 Exp per step I take or something?

Thanks