Alright, I'd like to bring up the clarification between a thread-based character, and an all around character. Creating a character is completely optional, there is no demand whether you create either one of these.
Thread Based Characters: Characters that are made for soley one RP thread. As in these characters may not "travel" to other RP threads, without making the character again.
These characters are made specifically for the timeline or setting, since not all Omni characters (most Airbenders, some earlier Avatars) may be in Post-Ozai era, unless deemed canon. This means, that a character you want to make for one purpose in one thread can be made so long as the Participants and Creator of the RP have no issue or concern.[/size] If there is some concern by a participant, but not by a creator, then the participant will notify an RP admin about their concern and situation. Thus the RP admins shall intervene.
Omni-Characters: These characters are created in the "Intro Page" and are done so because the author or creator of the character, wishes to use this character in more than one thread. These characters (though sticking to continuity for Timeline and canon) may go to any thread (so long as the creator allows) and join there. This is basically a character that can be played more than once in different threads. Since none of the threads "link" together for some major plot, it will run smoothly and no discontinuity will occur.