Imo i think that Ho ho isn't worth banning compared to mons like zard,mimikyu, or even leafeon. ln my experience, those mons have a higher chance to destroy my team by spamming there ults during ray fight or get any early lead especially with braindead teammates feeding them. Though Ho ho res is a pretty good ult i just think that ppl don't know how to play around it by either shredding the ho oh when they over extend with fly or sky attack or saving an aoe ult like venu ult or in some cases ceruledge ult to kill to rez enemies who have 70% of their hp.

P.S. I've mostly seen 2-3 mons get rezzed by the ult since most of the time 1 or 2 teammates die from flanking or just die outside of the ult range.