As long as it is possible to create new teams, what you're talking about is also possible.
you must create a new team folder, the new entry in the file teams.txt and be sure the file bindings.py also lists your bots.
to learn a bit about that (create a new folder, how to bind) -> have a look at the file 'AIChart' in my sig (this is a cooperative work, i'm not the lone creator).
Warning : save you RA2 folder first, if you fail modding your files, RA2 will crash !
However, in 'events' you can only fight bots from the 16 first AIed teams.
Changing the order of the teams so the first team Will become the 19th and the 19th the first is another challenge...