Who in boxing, kickboxing or MMA is more than competant at both stances? Anderson? Machida?
Jordan Mein is right handed and a natural stanced fighter that chooses to fight southpaw. His boxing is sick as faaaa. Watch him finish Cyborg with some elbows above, but it was the left hook to the body ( after Mein switched back to orthodox) that really hurt cyborg.
whats vera?
Jerome Le Banner
I've always fought southpaw even though I'm right handed.
It feels more natural. Always has. 
Rich Franklin is not left handed, but taught himself to fight southpaw because he thought it would be more difficult for his opponents to deal with
There is something you don't know....I am not left handed...
Gokudamus stole my name - fighters who are left handed but fight orthodox: Oscar DLH, Miguel Cotto, Barrera, James J Corbett, Gerry Cooney, Mikkel Kessler, Carmen Basilio, Michael Bisping and possibly Kevin Randleman
fighters who are right handed but fight orthodox: Anderson Silva, Nick Diaz, Rich Franklin, Chad Dawson, Michael Moorer, Robbie Lawler, Kid Yamamoto
Really my dude lawler is? I know he holds nasty power in his right which imo opinion the right uppercut and right hook are his best punches but I didn't know that
Im left footed but right handed, i fight orthodox. Great for jab-kicks 
Cruz2ninjafoya - Jordan Mein is right handed and a natural stanced fighter that chooses to fight southpaw. His boxing is sick as faaaa. Watch him finish Cyborg with some elbows above, but it was the left hook to the body ( after Mein switched back to orthodox) that really hurt cyborg.
Dude is nasty big fan I thought his fight vs stinson would've been more of a brawl but he picked him apart
simonpe -Im left footed but right handed, i fight orthodox. Great for jab-kicks
Ditto. Another guy in our gym is also cross dominant, so I help him with combos that better compliment his style.
The biggest name that I know of that hasn't been mentioned so far is Joe Frazier, naturally leftie, but fought orthodox. Wicked left hook.
Spncer Fisher is a rightie southpaw. Yves Edwards maybe too?
From wrestling for years it is very awkward for me to box orthodox, but honestly my boxing is garbage anyways.
Machida But most high level karate guys that compete will learn to fight off both sides.
Anderson and Franklin are right handede as well