I'm not a big fan of giving Legendaries to my ocs so the only one I could think of that makes sense is slapping Ho Oh onto Kingston bc of the ancestor lore and his involvement with bringing Ho Oh back to Johto after the events of Zirca. Kingston's character arc = distancing himself from other ppl to 1) protect them 2) bc he doesn't wanna lose anyone else important to him + Ho Oh lore being that it brings things back to life and its tower being a symbol of friendship and hope between Pokémon and people is like bringing that hope back to life for Kingston as well.