Who is the best fighter?

Think in a room where we teleport two member enemies between them, at the same time. Which race will win?

Mantis has more damage, but Rockmen have more life. Lanius will remove the oxygen of the room before they die in a fight, suffocating enemies, but Crystal members have suffocation resistance.

Zoltan, Engi, Slug and humans will always lose, I think. But between each pair of the rest what would be the result? Maybe when skills are maxed there is different results?

So which is the best race to fight against what?

Solution 1:

Just comparing the Mantis and Rockman in a completely neutral scenario:

Lets assume X is the damage an average race deals (such as Human or Zoltan).

A fully trained Mantis has a bonus of 1.7 damage with a health of 100.

A fully trained Rockman has a bonus of 1.2 damage with a health of 150

A mantis would take 150/1.7X to kill a Rockman, while a Rockman would take 100/1.2X to kill a mantis.

You'll see that the amount of time it takes a mantis to kill a Rockman is greater than the amount of time it takes a Rockman to kill a mantis for all Values of X*. Outside of damage variations, the Rockman will always win. Therefore, in a controlled environment the fully trained Rockman is the best hand to hand fighter.

*Once the values become large, the difference can come down to who gets in the first hit.

update

According to the research in this answer, a single lanius won't be able to drain the room fast enough to affect the combat outcome (assuming level 1 oxygen).