Fully adapted Mahoraga would never be able to win a fight. 

If Mahoraga truly adapted to everything, such as time, space, and death itself, it might seem like no one could conventionally beat him, but in truth he would immediately just beat himself. He would adapt to position, purpose, form / shape, consciousness, instinct, the ability to win or lose, the desire / necessity to fight, the ability to function on any level, adaptation itself, and even adapt beyond the idea of Mahoraga in every sense.

Adapting to literally everything removes the need for anything. Turn an ant into a universe and it loses the agency to protect its own colony. An all powerful being that transcends the concepts of being all powerful, all knowing, always present, etc, is something the human mind can't fathom, as to reach beyond both everything and nothing simply leaves something in a contradictory grey area, a truly miserable existence.

In short, Fully Adapted Mahoraga in a fight just doesn't exist. It's like asking someone to fight something they could never understand, comprehend, register, or remember (he would adapt beyond all forms of perception). So all opponents would win by technicality as there is no Mahoraga to fight or be aware of.


(I'm only half joking)

Fully Adapted Mahoraga would always lose actually