How to change the Bot's skill in DoomBot?

Because the bots were very hard to kill,so how to change the skill?And one more question.How can I play co-op in DoomBot?I added a bot in the singleplayer game.But it isn't my helper.He became my enemy!
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Forgive my BAD English.It isn't my native language. :-(

I think there is a console command called...
BOTSKILL
...in one of the Doombot Versions!
Botskill 10 is best and 1 is worst! Test it, but I'm not sure! And also take part at our "FREE HISSY" Community!