The Lancer-class Leonidas I, and Berserker-class Caligula have been announced to be joining the 20 Servants that will be part of the starting roster for Fate/Grand Order Arcade. [Thanks, 4Gamer!]
Leonidas I (Class: Lancer)
Noble Phantasm: Thermopylae Enomotia: Guardian of the Hot Gates
Caligula (Class: Berserker)
Noble Phantasm: Flucticulus Diana: Moonlight, Devour my Soul
Finally, the classes of the remaining Servants that will be available from the launch of the arcade game has been revealed.
This includes two more Sabers, two more Archers, one more Caster, two more Assassins, and two more Berserkers.
Fate/Grand Order Arcade launches in late July in Japan.