This ain't easy at all, but I did manage another one. LA featherweight contender Don Johnson. How many is that now altogether? It can't be many.
On the criteria laid out Mamby is there too: USA, Guyana, France, Nigeria, South Korea and Indonesia...
Papua in Indonesia is classed as Oceania, as indeed are France and the USA! So on the initial criteria you used, he did fight in the six 'Continents' you named. Indonesia being part of two Continents; Oceania and as you rightly point out, Asia...
The eastern part of the island New Guinea is a sovereign state called the Independent State of Papua New Guinea. The western half belongs to Indonesia. For some reason, the deviding line between Asia and Oceania runs right down the middle of the island. It may not seem logical - but that's how they have decided to do it.