I remember offering an idea of "heavy/light mechs"
idea is that, mech can equip more items than 1000, however, this is called heavy mech, and heavy mech is slow - so it have less actions per turn. Like 3 actions per 2 turns if you have 100-250 more weight (needs balancing)
same with going light mech. You get 5 actions per 2 turns, but for that you have to use 100-200 less weight on items
(might also alter HP and other stats, but with keeping original idea)
either way, if you implement leagues (using such realization as Elcent offered), you could also make between-leagues fights in such fashion. For example, league 4 fighter can fight league 5 one and league 4 will get 1 extra action each 3 turns, to compensate for his lightness.