So ghost type expert. I need a bit of advice on a certain stone with 108 souls inside it. Cause while I am caring for my team members decently I want to improve in doing so. Despite the fact that the spiritomb is a jerk all the time.
Heh, this is officially the first time I've been addressed as an "expert" and not just a specialist! Well, you said it, not me. (But thank you, thank you very much!)
So the thing about Spiritomb is that they're... ehhh, how do I say this nicely... They naturally lean towards the erratic. Think about it: There are Souls in there. Dozens of them. All different, all previously independent, all unique and with their own energies. They didn't choose to become this Pokemon. They're probably not happy about it.
Souls without bodies aren't as "independent" as the souls in you and I. (...or, well... there's an existential question of "do you have a soul or not?", but that's a tangent for another post, methinks.) But for the Pokemon, they're different enough that it can cause unrest, just by the nature of its existence.
As anyone who has had an awful roommate can tell you: Being forced to cohabitate doesn't necessarily mean you're forced to get along. Sometimes the basest level of energies in the souls doesn't resonate well with the others in there, and this can put all of them in a bad mood. Usually only one soul inhabits a body. That whole Spiritomb setup is really kind of unnatural for a spirit.
But the cool thing about Spiritomb is, barring any damage to their keystone (which can become a big problem very quickly; that becomes a PART of them in the process of formation), Spiritomb don't need a whole lot of bodily care. It's mostly mental for them.
So I would recommend finding ways to help the souls... "coalesce".
For some of them, they can find respite in tasks that require them to focus, sort of uniting towards one common goal. Battling tends to be the go-to, of course! Taking the actions can help them focus. Some of them do better with quiet focused activities, like meditation or puzzles.
For others, distractions are ideal. Entertainment like music or watching others train can take their minds off the chaos in there. Hobbies like cooking or contest coordination can act as both distractions AND focusing agents!
Like any of these ghosts that had a past life, they tend to carry, ahem, baggage. I'm, uhh... not sure where I stand on the controversy around "help an angry ghost get revenge", but at the very least, you can try to come to some kind of understanding where the Acting Out is coming from.
I don't know much about your Spiritomb, honestly. (Grave, is that the name?) But hopefully something I've said is helpful, and hopefully you two make some kind of peace with both the past and the present.