Name↓ MP  Type  Description 
Shiva 24 Summon Causes Ice damage to all enemies.
Ramuh 22 Summon Causes Thunder damage to all enemies.
Phoenix 32 Summon Causes Fire damage to all enemies, and all party members recover from KO.
Odin 28 Summon Instant death on all enemies (Wind damage if death attack fails but only if using Odin's Sword ability).
Madeen 54 Summon Causes Holy damage to all enemies.
Leviathan 42 Summon Causes Water damage to all enemies.
Ifrit 26 Summon Causes Fire damage to all enemies.
Fenrir 30 Summon Causes Earth or Wind damage to all enemies (depends on what Add-On is equipped).
Carbuncle 24 Summon Casts Reflect, Haste, Shell, or Vanish on all party members (depends on what Add-On is equipped - see Eiko).
Bahamut 56 Summon Causes non-elemental damage to all enemies.
Atomos 32 Summon Reduces all enemies' HP by a percentage.
Ark 80 Summon Causes Shadow damage to all enemies.