What do I do with this fella?

I’m relatively new to the game (started playing about a year ago) and while I was clearing out some storage I noticed that this guy (from what I understand) would be a hundo if purified! It would be my first legendary hundo and I love the mon, like the character design is one of my favorites. My question is, am I making a mistake? Is there something this mon is used for as a shadow that I am not aware of or is this a trash mon and send it! Thanks in advance and happy new year!