Regirock. it sounds like a terrible idea, noting how dangerous it is (with moves like hyper beam and explosion + being very heavy) but I wanna know how youd go around taking care of one. do you feed it?? does it need a certain habitat for enrichment?
As you pointed out in your request, adopting Regirock as a pet would not be something I could highly recommend for many reasons. You asked how, beyond issues of safety, one might be able to accommodate this pokémon as a pet; unfortunately, due to the lack of solid information regarding this pokémon, I am not really sure. Let’s get into it.
Regirock stands at just over five-and-a-half feet tall, smaller, honestly, than I would picture in my mind. Being made almost entirely out of stone (Sapphire, Emerald, FireRed/LeafGreen, Diamond/Pearl/Platinum, Black/White, Black2/White2, X, AlphaSapphire, Sword, BrillianDiamond/ShiningPearl), they are understandable quite heavy at over five hundred pounds (although this also is lighter than I would expect). Accommodating a pokémon of this size and weight within the home is going to be very difficult for a lot of owners, and on the surface causes some serious damage to Regirock’s pet viability.
As far as this pokémon’s personality and temperament goes, there isn’t much to go off of. We do know that, at some point in the past, humans sealed this pokémon beneath the ground (Ruby, OmegaRuby), but their precise motives for doing so aren’t fully known. Overall, Regirock is a bit of an anomaly, having no discernible brain in general even when examined with cutting-edge technology (FireRed/LeafGreen, Shield). They appear to be constructed from ordinary, natural stone, gathered from different locations from around the world (Sapphire, HeartGold/SoulSilver, Y, AlphaSapphire). They are a hardy pokémon, capable of repairing damage to themselves again with just ordinary stone (Ruby, Emerald, Diamond/Pearl/Platinum, Black/White, Black2/White2, X, OmegaRuby, Sword, BrilliantDiamond/ShiningPearl). How does Regirock behave? I don’t know. What is their personality like? I don’t know. Are they easy to take care of? I…. Guess? If you have the space?
Unfortunately, this is all rendered rather void by the sheer danger that this pokémon presents to humans. Regirock, as a legendary pokémon, is capable of using staggeringly powerful moves that, considering their large size and weight, could easily present a lethal threat. Regirock, to put it bluntly, could flatten you if they wanted to. There’s also the issue of rarity: again as a legendary pokémon, there is only an individual Regirock in the world, making it essentially statistically impossible to adopt them as your pet. I am not even sure of this pokémon’s current whereabouts in the first place.
Adopting Regirock as a pet is not a good idea, but it’s also essentially impossible. I apologize that I couldn’t give more information about how you might be able to accommodate them as a pet anyways; we simply don’t have enough data about how this pokémon behaves around humans and other pokémon. If you’re looking for a pet made of rocks, there are better Rock-Type pokémon options for you out there.