After fighting his way through Charloga Arena's fighters, Ackster's final opponent was Hoga, a mace-wielding fighter employed by the island's ruling clan to stay on Charloga instead of challenging the other islands or trying to challenge the central island.
Of course, Hoga had already tried to challenge the other twelve islands, which was why he could be persuaded to stay. Otherwise, no amount of money could control the spirit of a Matar fighter.
The fact that he had agreed to remain on Charloga as a champion and fight any challenger didn't mean he had given up on defeating the central island's champion either. It just meant he was honing himself through repeated combat. He was biding his time and building his strength.