So I got lucky and rolled three Quetzalcoatl's in my first 600 Gacha tickets, so I decided to shift my focus from the red boss to the blue one. The difference is like night and day; the red boss was easily done with auto attack, whereas the blue boss seems to hit like a truck when it gets that attack buff off, and when auto attacking I can't reliably remove that buff unless I manual the fight. Even using Sol + Andro + Brinhilde I can't manage that battle in auto as it's down to luck whether or not that enemy buff removal comes off of cool down in time or not. Even so, in manual mode the blue boss is very easy to solo when I use a combination of Sol and Andro with Chaos Magic; as long as you can keep that attack buff off of her it's an easy fight (sitting at 28k attack).