I think this is possible with bot events.
Lies!
When a bot spawns, do the following:
Onbotspawn -> bot -> SETTEAMNAME -> team 1
Do the same for the 'enemy' bot but set to team 2
Then, on the team one spawns, do onbotspawn -> bot -> botattack -> attackteam "team 2"
and then do the same for the enemy, but with attackteam team1
Then respawn the bots and they'll dive on each other as long as they have a weapon