I think the Reborn battle has the most variety in the difficult selections. If your difficulty is Padawan, you fight a Reborn Acrobat. If it is Jedi or Knight you fight a Reborn Boss. If it is Master, you fight a Reborn Boss and a Reborn Acrobat/Fencer/Force User.
@shadowfax02 The energy door... where? If you mean the energy barrier after "Darth Moronicus"(the boss) then you have to go to the shield generator, go to the one of those rooms filled with consoles, find the console with the blue light still on and deactivate it. (I know the explanation isn't very good, but you can't expect me to remember the entire demo in absolute detail)
You should do the Artus Topside mission, complete with the lightsaber and force power cheats, and spawn several Reborn for you to duel throughout that mission.