Now that Bellator fighters are going to Japan to go against Rizin fighters under Rizin rules in a roped off ring, I decided to look up their rules:
All attacks to the head are allowed, regardless of the fighter being grounded or standing up. This includes soccer kicks, knees, and stomps. However, if there is a weight discrepancy of 15 kg (33 lb) or more, the lighter fighter is allowed to choose if such ground attacks are permitted. Any kicks, knees or stomps on the head of a grounded opponent are considered fouls in the Unified Rules.
Unlike PRIDE, Rizin FF allows for use of elbow strikes, which are permitted in the Unified Rules. Additionally the 12-6 elbow, illegal under the Unified Rules, is legal in the Rizin FF ruleset.[35]
there are many nerds here who will readily point out that those were banned after some asshole watched gan mcgee elbow rocky batastini into bolivian in an old ifc event. mcgee sliced him good. it was bloody
that guy then complained to john mccain who used it as fodder to ban mma because it was cutting into boxings revenue and mccain was a crook. the whole human cockfighting rigamarole back in the day
then someone paid someone else off and unified rules were born. logically it makes sense that anywhere not subject to a us athletic commission would not adopt unified rules
for instance there are somewhat recent events in hawaii that allowed knees and kicks to downed opponents. anything goes on the rez