What exactly do Ash's pokemon do at Oak's lab?
Bulbasaur is sort of a pillar of the community, solving disputes and stuff. Muk plays with Oak and, in doing so, probably prevents him from getting too caught up in his work. Kingler helps around the lab. Snorlax obviously sleeps and eats and we've seen Tauros just generally run around in a herd. The rest probably play, train or do both.
There's probably a fee or subscription type thing. You probably have to sign up and open a PC account and pay monthly for someone, in Ash's case Oak, to look after your Pokés.
Maybe Ash gets a deal cause him and Oak are tight.
but i've already fapped this morning
Train, play, and enjoy a nice retirement deal after traveling with Ash. Oak does research with them as well. For example he wanted Ash to leave Heracross at the lab so he could study the species more and then told Ash he would like to study Notcowl since it's a shiny pokemon
Oaks a world renowned Pokemon research. He probably makes tons of money and uses it to help feed and care for the pokemon.
The ones who aren't there for the food worship Ash like a deity and count the days since he last used them, just waiting for the time when they can finally rise up to the occasion and prove that they are worth a permanent slot in his team like Pikachu.