There is a rule now. You can't join the fight - but you can be in a new point of view, watching the fortress and the fight between Phoenix and LS. I'm sorry it may sound unfair but every character has already done something.
So SonicPlayz, you can uhh choose where LS takes them. Fun fact:LS' suit uses his MIND as a control system PS: THIS IS SICK AFTER DIS IS DONE LETS MAKE A STUDIO (And Possibly a sequel)