Long story short, I'm using a save file in which the original owner somehow completed Mt. Battle early in the game the 3 times to get all the Johto starters, they also modified some Shadow Pokémon to be different Pokémon (here's how the list should look like) plus they also have the wrong trainers.
The Johto starters, as well as the original Pokémon the owner had, were all shinies but with Max IVs and EVs, I deleted them all and transferred my own Pokémon to this file so I'd just like to know if there's any way to reset Mt. Battle, and fix the Shadow Pokémon that were edited.
I have shinies of my own now (Eevee, Pokéspot, Duking's, Elekid) and am around the point of Michael losing the Snag Machine (atm have 31 Shadows) so I'd prefer to not have to reset.
Oh and also, my original save file has been lost unfortunately so can't do much about that either.