From what I remember you can do the following:
Use/upload
12 created teams. If you pre-ordered from
Game Stop you will get
25 slots for created teams, but if memory serves
12 is the limit you can have in the game at any time.
Your
12 teams can be placed in any conference, or they can be spread out throughout the country. Let's say you want to redo the
Big XII or
SEC, the teams you upload will take the rivals of whatever team you replace them with.
In other words, say you create the
Alabama Mud Sharks and they replace the real
Alabama Crimson Tide. That team will inherit the
'Tide's real-life rival(s).
Make sense?