OHHHH BOY. I didnāt think anyone would actually take me up on this aha nvn; Iām going to be putting it under a readmore, EDIT: READMORE IS GOING AWAY BC TUMBLR IS DUMB its pretty body horror-heavy and contains references to real life conditions and medical talk and that can make some people real uncomfy.
Emmet inarguably got the best deal here, despite being miserable. Arceus did a really good job of making sure he would be comfortable in his new body and maintain his individuality. He has full sensation in all his body parts, and his difficulties using them is more down to inexperience with having those particular limbs than any issue with them. Of course, since Arceus isnāt super great at the whole ārelating to mortalsā thing, thereās still a lot of things about his anatomy that bring him pain. For one, the human spine is really not meant to handle the weird center of gravity he now has, and inexperience with his new legs also means moving them in ways that end up putting strain on them.
Contrasting this with Volo, thoughā¦. Yikes. Giratina more or less feared for her life (since unlike Arceus I think that the creation trio can be killed under the right circumstances), so fusing with Volo was a last-ditch attempt to get out of a sticky situation. As a result, she had no desire to actually make sure Volo could function in his new form, and the results areā¦. Bad, to say the least. Very bad. He has some control over his limbs, but his ability to move is extremely hampered by poor nerve connections and, well, pain. Itās not all bad for Volo, though, as unlike with Emmet, who basically only got the powers he made a deal for (kind of. Once again Arceus is not very good at this) Volo has access to all of Giratinaās abilities, and then some. The trade off being that, while he could easily crush Emmet all by himself, heās pretty much stuck in place for the time being and needs to use alternative methods to attempt to get his revenge. Youāll be seeing what I mean soon enough.
This part is where that content warning really comes in, so if body horror and medical talk squicks you out no need to read on.
Beyond just not being able to control his body, the haphazard fusion job between Volo and Giratina had a second, arguably much worse consequence. Basically, Voloās body parts and Giratinaās body parts are not compatible. It is a bit like a fusion (no pun intended) of an incompatible organ transplant and an autoimmune disorder in the worst possible way. The cells of Voloās body are actively rejecting Giratinaās body parts, and the results are that heās more or less rotting from the inside out. While this would typically be incredibly fatal, Volo is kept alive by Giratinaās powers and his now single-minded desire for revenge. As one might imagine, this has had a pretty severe effect on his mental state as well. While Volo before the fusion wasnāt exactly stable and well adjusted, becoming an eldritch abomination leaking necrotic fluid has exacerbated things considerably. Hatred is whatās keeping him going at this point, and itās going to take a lot to save him and Giratina from the situation he put himself in.