* All members are advised to have a Key Item: Vahzl gate crystal to minimise travel time.
* WHM recommended (not just for Teleport-Vahzl!)
* Supports 1 party.
* Aggro to Sight
* Links by Sight
* Weak against Light
* Strong against all other elements. (+25% Magic Def)
Demon Knight (DRK)
Demon Pawn (WAR)
Demon Warlock (SMN)
Demon Wizard (BLM)
Camp right at the entrance to Castle Zvhal Baileys, and pull the surrounding Demons. Note that the Demon Warlocks are slightly harder than the rest of the demons to kill.
A White Mage is useful here, not only to Teleport-Vahzl in order to get to camp in a quick and clean fashion (although make sure everyone has the Key Item: Vahzl gate crystal!), but also because Haste overrides the Demons AoE Slow effect.
Other than that, unless your puller is very skilled, you will probably get the occasional link from time to time. In the event one of the demons is a Demon Wizard (BLM), focus on killing the Wizard first. Worst come to worst, you can always zone into Castle Zvhal Baileys should things get out of hand (dead member, more than one link, etc.)