When you're talking about a Square Enix game featuring the Dragon King, Bahamut, it's a given that the other Aeons / Guardian Forces / Eidolons / Espers will be tagging along for the ride. This time, instead of being trusty helpers that bring the pain onto seriously outmatched monsters, the stars of Summon Magic will be doing their thing against you and your party.
Although it wouldn't be the first time for you to be taking on the beings that you summon in Final Fantasy games and spinoffs, it's still nice to see the tables turn and see if your loyal subjects could take you out, but it'd suck if they did.
From these screens, we have who appears to be Ifrit. I'm not too sure if the icy lady is Shiva 'cause I don't believe that Square Enix will give her that much clothing - I'm kidding. As for the rest, I can only guess, particularly one with either Alexander on it or an actual castle. The horned beast that uses purple lightning magic reminds me of FFVII's Kjata too.
Blood of Bahamut still a long way from release day, but a playable build exists now. If you happen to be in Tokyo and you feel like testing it out, you can sign up through the official site, provided of course that you can navigate through all that Japanese.
More info on Blood of Bahamut: