I agree with Dmorty, it's all dependent on the size of incoming fish. If the fish are small enough and tank large enough, you can partition the QT tank to avoid any aggression and still acclimate the fish to each other.
The Achilles is going to need some high oxygen saturation in this QT, so be sure you have ample waterflow (not a typical attribute of most QT tanks including my own) and/or a few airstones to keep the O2 levels high.