>>26782627Fighting beats Normal because a trained martial artist will easily defeat the average Joe.
Fighting beats Rock and Steel because they have superhuman strength, and characters with super strength are often shown breaking rocks and bending metal with their bare hands.
Fighting beats Ice because ice is fragile, same reason it's weak to Rock and Steel.
Fighting beats Dark because Dark-types rely on underhanded tricks (throwing sucker punches, biting, etc.) which are ineffective against martial artists.