The battle of place: Ruhenheim
It's manipulator vs. manipulator.
" @willyvereb: Uh, about that. First, Johan will be immune to Geass because he is insane as Joker is as the latter is immune to Scarecrow's fear gas. Second, Johan will just point at his forehead asking to be shot until Roberto, his henchman, shoots them one by one. Once that is done, if you seen R2 episode 19 where Lelouch says that he doesn't want to live anymore, Johan takes advantage of that and drives him to suicide. "This is true, the Joker did withstand Scarecrows gas, so Johan can be immune to Geass. Also, if you remember where Lelouch is killed by Suzaku (like Light with the death note) This will give Johan the advantage because he can drive Lelouch to suicide, like when they find out Light is Kira.
Johan - Uses his cold intelligence and wit to make others do his bidding and plans on a level that puts Light to shame.
Lelouch - Geass time! I command you to die! I command you to obey! I command you to answer my questions...
If it weren't for his Geass Lelouch would have gotten nowhere. Johan actually uses his head.