Here are the Summons that will be in the game, so far:
Odin, Lightning's Summon: YouTube - Final Fantasy XIII Odin Summon
Shiva, Snow's Summon: YouTube - Final Fantasy XIII: Snow Summoning the Shiva Sisters Nix and Styria
Carbuncle, Oerba's Summon: YouTube - Carbuncle FFXIII
Ifrit: http://3.bp.blogspot.com/_qT7I30qesJ...XIII+Ifrit.bmp

If you would like, you can discuss whatever needs to be discussed about this.
Comment if you wish.
Enjoy