Magnie basically has only 6 pokemon, her main team is pretty important to her and she doesn't like caging them up all too much (even if she whiffs all her gym leader duties)
Amber (who is still in a designing process wow) has a lot of electric types due to her profession (e4 and electrician)

Most of them I only picked out 6 for as gym leaders but renahv keeps 14 on hand

Outside of her main party she only has Victini (which is not an actual member of her team, she never even caught him, he's more of a traveling companion)!

But I guess you could also consider Briar's experiments as Pokémon that she legally "owns", although most of them are not ready to battle and are contained in her lab. So, in that case, two other Pokémon I could mention are Type: Null and Eternatus.

HMMof all my ocs its just mira who has extras outsife her team (more like an alt team for her to use when she's undercover as a phantom thief

Jin doesn't really go out of her way to catch pokemon so only has a maximum of about eight.
Mary on the other hand has a decent amount, just shy of a dozen or so as of right now.
Celeste has about fourteen. (a majority being her Minior)

Honestly, I've lost count. But for simplicity's sake, let's just say Elio has a lot of Pokemon under his care - in one form or another.

18, with their main team 24 and plus the three I’m going to add it will be 27 when SV comes along!

Currently 45! 2 of which were released, and there's the time where he caught 29 male Combee in attempt to find a shiny Female, which he does-

He would normally rotate his Pokemon all except for his Dragonite and Cloud, some notable reserves being Decidueye, Inteleon (For his acting job mainly), and his Rotom that is in his phone. Though Rotom is very timid, so it prefers to be in his phone instead of battling

Jasmine has a Bellossom that takes care of her house when she is out.

Gael has like. A whole herd of a bunch of different Pokémon that he takes care of on his ranch dhdhd

Other than that, most of my ocs just have their main party of six. An exception are my Gym Leader ocs, who have some weaker Pokémon that they use in gym battles