I'm playing FO2, just downloaded and installed it, so it's the latest instalation, with the restoration mod.
I got sulik to join me, and he follows me around outside of battles, but when a battle will start, he will stay in his place. If an enemy will stand next to him, sulik will attack him, but otherwise he is completely still. any idea what's causing this?

Talk to him and ask him about his battle stance. I think one setting is defensive where he will only attack if he is attacked or of someone is close to him. You probably want the Aggressive stance.