Hold down the alt key when you select a ship and you will get all of them in the gravwell and can issue the order.  You can also get good at selecting multiple ships with the shift key and then issuing the order.  Finally, it can be helpful to select your ships in the empire menu to the left just like you were clicking on the ship, and doing the above to get multiples.

As a sidenote, you can't have all the overseers use their abilities at one time, you have to stagger them so as one fades, the next takes over.  It does in fact take some micro for best results.

I tried the alt clicking but all it does is select all of the same ship when i issue a order to use the abilities only one ships abiltities is used. I will try again Would be nice if you could make like sub groups in a fleet.

I'm actually not hopeful.  What would be the reward for learning to play the game better if the AI did the micro for you?

There's good micro, and there's bad micro. Needing to aim every single Ogrov, for example, is bad micro. As you said, most buffs aren't stackable so it's a non-issue there, but if you want to manually switch your Assailants' mode, do you want to do it for one ship at a time, or the whole selection?

Although, it would be nice to accomplish some abilities on a whole, if need be.

In my experience, the AI is absolutely terrible at triggering this mode.  I've had the AI use it as soon as it arrives in an enemy grav well and not switch back, even when ordered to jump to another planet.  One time I ordered a fleet to jump, then went to take care of some other defensive stuff.  When I came back to my fleet about 5 minutes later, it was still there because a group of assailants was on the other side of the grav well, locked down in the stationary mode.

Also, Cielos could auto use their targetting ability a little better.  For an auto target, it should pick the biggest, baddest ship in range.  I've had Cielos use it on half dead light frigates that were right next to a fairly undamaged enemy cap ship.

Exactly, specifically the frigate/cruiser AI.  The AI is usually on the ball with most cap ship abilities, and I don't really mind the AI not being perfect there because if you want to get the most out of your caps, you should have to micro them.  But frigates and cruisers, in general, could be a little more, well, intelligent in their choices.  It's fine having to micro them when you just have one fleet starting out....but on large maps with 3-4 fleets spread out, babysitting 20 Hoshikos, 30 Cobalts, and 10 Cielos in one fleet is rarely an option.