After all the rulsets are based around what they do, this is quite an advantage.
Can you give a ruleset that doesn't?
Basically we base what we do around fighting one on one with no rules, or as few rules as possible. In a sense, allowing everything from all rulesets. Which was the initial idea, let everyone in, let them all do everything there rules normally allow and see who comes out on top.
I really don't see what else could be included and still have a fair and safe sporting event...?