Like virtually everyone else here, I like the concept of the idea. It's something I've thought about myself a few times actually. With that being said, we also have to take into account certain factors that would naturally apply to the minigame. 1. Balance. Balance is important. You don't want certain pets dealing a crap ton more damage than others or having OP abilities. 2. Wide variety of abilities/moves. If pets are going to modeled after Pokemon, it only makes sense for a pet's move pool to change as it levels up, so there needs to be a wide variety of moves available to each pet, and plenty of moves that more than one pet can have. Likewise, moves should have different purposes. Maybe most moves deal damage, maybe some dish out status effects (like a burn that deals steady damage each turn). 3. Evolving? Again, if pets are going to be modeled after Pokemon, it could be cool to have them evolve into their adult selves. Baby cows turn into adult cows, baby chickens into adult chickens, etc. Those are just three things I thought of, but this whole concept is very open. If you need ideas, just look at the Pokemon games for inspiration: held items, natural abilities, caring for your pets, etc. There's so much there to offer to an idea like this. ...However, it's also worth noting that this idea is cosmetic. Which means it's not going to take priority over anything deemed more important, like game updates and quality of life changes. Combined with the effort needed to flesh out a battling system, it's possible that it wouldn't be worth the developmental resources... even so, I don't find that a valid reason to disagree with it, so here's a +1 from me.