So about them summons. A lot of referencial names don't add up to their real-world counterparts. I think most of them might be cooler to see if they were modelled after real-world legends rather than just bearing their names.

Supposedly, according to the game, Bahamut is the legendary king of dragons . . . but nowhere in real-world history and legend is Bahamut titled as this. Bahamut is a giant fish (like Geosgaeno - FFX) on which stands Kujara (Kjata) a giant bull which bears on it's shoulders the world's angel (the angel that holds the world). Geosgaeno was a cool enough monster. I think it would be a cool enough summon called "Bahamut."

Bahamut ZERO looks similar to FF8's Tiamat whom is a legendary monster similar to a dragon and is the female nemesis of some great god whose name slips my mind at the moment. According to the game, Tiamat is the queen of dark dragons or other such nonsense which makes her the archenemy of Bahamut.

Everyone knows the inconsistency about Odin. He's not supposed to have a sword called Zantetsuken, it's supposed to be a spear. His horse is supposed to have eight legs, not six. Aside from that, I suppose there's no real inconsistency about him.

Alexander . . . I don't understand the whole robotic castle thing. Alexander was a great warrior who fought against inhuman odds.

Knights of the Round is very funny to me. There are shown twelve knights and then King Arthur is the 13th. However, to my knowledge, there weren't twelve knights to Arthur's Round Table. There were about 300 or more. The Round Table was nearly as huge as Arthur's massive dining hall and could easily seat at least 100 men. There aren't even twelve most popular names from King Arthur's legends. Here are the most common names to associate with the legends of Camelot:
King Arthur Pendragon, Lancelot, Galahad, Percival, Merlin, Guinevere, Morgan, Mordrid, and possibly Lady Nimue.
There are, however, twelve apostles depicted sitting with Jesus Christ in "the Last Supper." It's an obvious reference.

Eden of FF8 is an interesting creation. Eden has never been depicted as living being and thus it has no biological reference. Eden, however, is depicted as a sort of biological version of eights SeeD Gardens. Hence, the Garden of Eden.

I have no idea what inspired the FF9 designers to make the Ark into a transformer, but I found it entertaining, even though the Ark is not supposed to hold weapons of any sort.