Character/Concept Artist(s) For Selene and Elio in Sun & Moon

I looked through the staff credits of Sun, Moon & the Ultra games and I couldn't for the life of me find an artist credited for designing Selene and Elio (in the original SM or USUM games) - so I was wondering if anyone knew who their artists were? Specifically the artist(s) who made their designs, not just the artist who drew their key/official art, but I am curious about that too. Was it ever officially said in the first place?