Mhm ... minimum assembly for a GM box is 3+ people:
1 Kungfu GM with WDD, DMS and PS and Taunt aKa Tank
1 TS with Heals, Rez and Combat Aura 1.0 aKa Doc
1* SMG Spec with FAR and FA aKa Support
Buffs like UM, MA prowess, Firarms skill or resistance debuffs like Inisidious or Destroyer or Sky-High Kick are rendered completely useless once the Kunoichi hit above level 60 (61 and upwards) and are thus not needed in any way. The damage you do is constant from lvl 61 upwards and does not decrease.
Tactic:
Tank - The Tank interlocks the Kunoichi immediately and uses Taunt (if it's not his box). Do NOT waste IS on normal abilities. Wait for specials. Use Speed and Kungfu style. (with Power Tactic Switch). If the Kunoichi tries to withdraw it means that somebody else got more attention than you. Use Taunt immediately to redraw attention upon yourself.
Doc - The Doc heals when necessary and runs Combat Aura 1.0 WITHOUT pause. This is very essential for a flawless victory. When not healing the Doc keeps shooting the Kunoichi for increased state chance (preferrably on Power, Victory Rifle is a wise choice here (+15% stagger))
Support - The Support keeps on hitting on Speed till the Kunoichi is stated. Use FAR. If you have more than 1 Support keep a balance between people who shoot on Speed and people who shoot on Power for maximized state and thus damage output.
The reason why to use Combat Aura 1.0 is because as soon as the Tank uses an ability you can easily override her accuracy or defense and thus keep her from hitting. That is why it's very important to keep her stated as much as possible so the amount of normal rounds will be kept to a minimum (in which it's very likely that you could be hit). That's moreover the reason why the minimum is not 2 (Tank and Doc) but 3 (Tank, Doc and Support) so the chance of states is much higher and you don't need to waste IS on normal abilities to negate her accuracy/defense (state specials are better than normal abilities because of IS consumption, accuracy and damage).
If you want to do the GM box faster, only increase the amount of Support types. You do not need more Tanks or Docs, though.
That is not, however, how you do the high level box. The number of Tanks and Docs has to be increased and you need quite a fair amount of Supports.