Also, I'm not sure if I missed this but how accessible are our powers? Limit breaks aside because hopefully none of us will get to the point that we need to use those.
Great question.
All right-y, now considering that the players are unaware of their Aeons and such, their abilities are considerably unknown as well. So, how does one access it? Honestly, purely by accident of the situation, the abilities themselves can activate by their own volition in protecting the host or the SOLDIER in question has that peculiar inclination that suggests a certain action, like a deja vu that convinces them that this what needs to be done.
The abilities are able to be used with much more consistency, unlike the Limits which are purely last-resort. So essentially the abilities can be used whenever you deem appropriate, I trust that none will try to spam their powers, as they have a lot of psychical training as well to be a considerable threat even without their abilities being used.
Also, remember - if the Eagles are immune to John and Evangeline, they are essentially immune to the Eagles as well. Colours share weaknesses and immunities.
Use this as a guide:
WHITE - Immune to Blue and Green; Weak to Black and Red.
BLUE - Immune to Black and White; Weak to Red and Green.
BLACK - Immune to Red and Blue; Weak to White and Green.
RED - Immune to Black and Green; Weak to Red and White.
GREEN - Immune to White and Red; Weak o Black and Blue.
And I forgot to include the Battle Environment - PLAINS. So white colours gain an Environmental Bonus.