There's a bot program that creates bots for
many different mods called Akimbot.
Currently it isn't up to date with Alpha 2.0 of ESF, so if you install it and host a LAN game or something you and the bots won't have all the weapons (ie: no final flashes for Vegeta). But don't worry, you can still connect to internet servers and play fine, and there's an easy installer/uninstaller if you ever need to remove them.
Also, the bots aren't VERY smart and can't join teams yet, but they are hard enough to provide a FFA challenge.
Here's the site:
http://akimbot.nuclearbox.com/
If anyone knows of other bots I'd be interested.