>Al, Yae
vs
>Rem, Ram, Emilia
and
>Roy, Alcanica, Heinkel
vs
>Meili, Clind, Rom, Petra

and Roswaal with Frederica somewhere

Petra is non-combatant
Rom = Heinkel
Meili, Clind, Frederica < Roy
Roswaal > Alcanica
but could be Roswaal vs Roy (Roswaal stronger) and the rest vs Alcanica (Alcanica Stronger) so that side is even

and for the main fight I would bet for Al and Yae team, Emilia is a great counter for Al but he outplayed her once

just read the prologue
Aldebaran is Echidna's student, but it doesn't implicate that she created him. Given his powerful Authority I think he was created or summoned by Satella.