Hey guys, if anyone actually plays this (I did!) and is getting frustrated with the gold trophy that says you have to beat Kaos without swapping any guys out here is my advice.....it was a huge pain in the butt for me and I kept getting killed when he summoned out, Chop Chop, Ghost Roaster and that other whore.....anyways.....this is what I did to make it work, and it was a LOT easier.
Firstly, use Double Trouble. Make sure that you have him upgraded to the point where when you press the SQUARE button he throws out that huge coin, also...make sure you have the upgrade that when he throws the huge coin out, if it lands on heads it deals extra damage...that is key. You literally will almost never use your pistols. Ok...so, once you have that....when you see Kaos coming down (when the red rings light up and he's about to land) SPAM the SQUARE button and keep trying to get the heads up coin....even with the hydra cutscene when it cuts back, you can have 3-5 of the heads up coins damaging Kaos, and if this is the case, you don't even have to kill the minions. He will do the auto cut scene where they die and the next ones come and absorb there little energies. This worked for me on every single wave of minions and made Kaos 10 timers easier. After all the minions die and he is JUST using the hydra, rinse and repeat. He won't leave the area again and if you can load up 2 or 3 heads up coins he goes down in about 15 seconds.
Hope this helps guys......i tried about 10 different combinations before this one worked for me and it's the best method imo so far......thanks for reading! If you use this and it helps you out don't be shy, hook a brother up with some +rep!