BoxRec

who wins

prime ali in a fight where he can only throw punches with his left hand

or

anthony joshua (can use all punches)

Of course, a solid enough fighter will win a one-handed competitor, regardless how good he is. I can imagine Ali winning some Lovejoy with one hand, but no way it could be possible against a world class fighter. That is even different to just not throwing right hand, i.e. when you can throw it, when opponent waits for it. It's absolutely different psychologically. Wlad Klitschko KOed Ray Austin in two rounds without throwing a right, but he could do it in any moment. Austin didn't even realised that, when he awoke. But when you know, that there will be no right hands for sure, you will box different strategically and psychologically. It's like fighting a crippled guy.

Joshua

Joshua wins if Ali can't use his right hand.