User blog comment:DannyPlaysGames/The Horned King vs Yubaba - Anime Rap Clashes Halloween Special/@comment-38608712-20191023020052

That rap battle left me Spirited Away. Here's some casting suggestions:

Vladimyr P. or SethIsMe or The Supah Master or Alex the Beast or Light as The Horned King.

Freshy Kanal as Yubaba (he does make a great Yubaba impression as seen in his own duel that pitted Frisk against Chihiro).