How To Get Snows Eidolon
A easy way to beat the sisters is to upgrade all of your abilities to the max then start out in commando and attack 3 times then switch to Sentinel and use provoke, provoke, guard. Keep repeating the provoke, provoke, guard when they attack you and the bar will fill up faster then you can get it any other ways. That's the only way I found because they only raise the bar with defense moves. Happy fighting!
How To Beat Light's Eidolon
Start out with light as a com. And hope as a med. Then after the first attack change both to a rav. You may need to revive hope a few times but it is worth it because hope is a giant target for the Eidolon. He'll attack hope until hopes ko'd then you. But if you keep reviving hope and stay a rav. You should be able to beat it under 2 mins.
To obtain just over 300000 cp in a relatively short time defeat mission 55 and equip the growth egg, then go to the faultwarrens and follow missions 35, 36, 38, 42, and finally 51. With the growth egg equipped and fighting all the battles on each map you'll gain roughly 314000 cp. NOTE* don't attempt at low levels you WILL die.