What about a situation in which mecha are used in conjunction with more traditional military units and infantry? Similar to a sort of mechanized infantry unit. 

In this situation the team's most likely single mech would play as a sort of force multiplier, with its heavier weapons. Infantry would then be used in a more tactical sense. The mech would be like a sort of evolution of tanks, more flexible but just as powerful. 

Taking a step back and looking at what I just said.. I'm reminding myself a lot of titanfall, to which I regard as.. Meh..