How do you think of those robots? As for me I always let my leader pilots ride the Devil Gundam Jr & Grand Master Gundam (as I always find them kick ass), the only item they need (as an mobile armmour) is 'I field'.
Which gundam you normally let the leader pliot ride?
My usual criteria for master unit would be 1. Decent overall terrain rating with at least B in air rating (this way I can save one or two OP slots) 2. Multi lock weapon 3. At least range 6 weapon present without being funnel type weapon or a weapon type using 20+ MP