Say you've only trained Jiu-jitsu. And you go into a boxing ring using only boxing rules.
Reverse it, you only box and go into a jits match only using jits rules.
You can pretty much replace boxing and jits with whatever styles you want.
Look at the first UFC competition. It came about from one man's question of an age old fight question, who would win, a boxer or a wrestler? It then expanded (before the first UFC) to a style vs style tournament with very few rules. But even that wasn't a panacea to answer the question because the levels of talent of the respective fighters was not equal. The reason they weren't equal was because the promoter, Art Davie, couldn't get anyone to fight.(seriously, he tried)
I would have loved to have seen people like Mike Tyson, Dan Gable, Ernesto Hoost, Jean-Yves Theriault etc in that first UFC. That would have been one hell of a show. But that wasn't about to happen.
Even if it did......what the UFC has morphed into since, is a specific sport. Regardless of style, you aren't going anywhere if you are not training specifically for UFC rules and reality. It has nothing what-so-ever to do with what your main style might or might not be.
You can look at all the videoed fights you want, it really doesn't answer the question being asked, which is.....oh, hell, I forget what the hell the question is.
Carry on.