@Gorlom:
Isn't the daimon theme the devil bat? =S
Or what do you guys mean by theme?
Basically, each team has a different "theme" regarding everything we see about them, from their appearance and play style to character interactions to even the buildings and school ideas connected to them. From what I've seen, some notable examples include:
-Deimon: the "scrappy, adaptable, yet powerful little guy" (Hiruma, Sena, the fact that the school is a dump and that practically anyone can get in)
-Ojo: "royalty and ultimate defense" (Shin, Sakuraba, the castle-like school they attend)
-Seibu: "Wild West-style quick draw offense" (Kid, Riku's "Rodeo Drive", their training grounds Doc Horide own in Texas)
-Taiyo: "Egyptian-style stone-wall defense" (Pyramid line, their school looks like Egyptian ruins and practically every student has a tan similar to a citizen of the Middle East)
From many of the things that Teikoku has demonstrated, their theme just seems to be "the Macedonian/Roman conquerors", the unstoppable empire that rules over all and takes the best, brightest and strongest for themselves to continue their unstoppable reign. (somehow makes me wish the final opponent was a "barbarian" team like Geshinjin :p)