Got 94 kills in gauntlet. Same color is best. Use yellow healer set-up that SkylerLight mentioned.
Three yellow healers in the back: Orderly, Doctor, Nurse.
Attackers in the front: Esther (She will be your 1-hit KO in the late-game because of extra dmg gain), Gunner, Newbie.
Don't use auto-attack. Focus on stunning bugs and killing high damage enemies. When the game starts, look at the enemy team and decide which 3 enemies you want to keep alive for the rest of the game. Enemies will become stronger and stronger and you'll want to try and keep those that do 1 or 2 damage max (Robots do more than 1-2). Your healers will take care of that damage.
Again: Avoid using auto-attack, there is chance that your team will kill the target and then kill a low damage enemy. You don't want that because that means one more high-damage&hp enemy will come in 3 turns and the difficulty will increase immensely.
Make use of over-charge to gain more dmg & hp yourself, don't attack if you don't have to.
Rampage jaws make it quite easy to finish. No need to ever touch the surface because you have wings and a giant mouth that kills everything around you. So mines never ever hurt you if you keep tapping the arrows to keep you flying.
The female endings were really weak.
A blind female hero, a blind female failed hero, a sex object, a woman that's out for money and someone that influences fashion. THAT's the best you could come up with?