just make everything customizable is the safest bet.
if i have more than 1 teammate, i need them to have different colors.
if i have more than 1 enemy, i need them to have different colors.
and obviously, my own units should be a different color.
this is all for strategic and communication purposes.
i don't know if MMO mode will have more player than colors in which case you need to get creative
. maybe custom crests or something.