there are 2 modes: feast and frontlines.
The Feast has 4v4(ranked) and 8v8(practice):
-4v4, 1 tank, 1 heal, 1 melee, 1 ranged/caster
-8v8 no job restriction

Frontlines, must be your "FC" has 3 modes: secure, seize and shatter. These are 8v8v8 up to 24v24v24.

the fastest Qs are frontlines and 8v8