Ra's Al Ghul vs Joker (read first)

 Fight takes place: An abandoned shopping mall (consist mainly of fast food joints and clothing stores and some part still under construction and it's dimly lit)
 
 RULES:
Ra's has a sword and 8 ninja death stars 
this is AA (Arkum Asylum) Version of Joker
He is armed with: pistol (2 clip), joybuzzer, acid spitting flower, brass knuckles, knife and X-Ray glasses 
Joker has 25 thugs with him (all armed with baseball bats and Uzis (5 clips) ) 
Ra's Al Ghul has 10 ninjas with him (all armed with 3 ninja death stars (and trained in h2h combat) ) 
Teams start at opposite ends of the store
first to kill all members of the opposing team first wins
Both have 3 hours prep time to set up traps and strategise

Ra's.

So they just face off against each other? No prep?  Ok.
The 10 ninjas would deal with the thugs, pretty easily, perhaps take 2-3 casualties.  That leaves Ra's Al Ghul and the majority of his ninjas to deal with Joker which is more than enough to kill him.

Joker gets owned hard

BUMP

Ra's Al Ghul still wins.

With prep time, it makes the battle more interesting. However, I still think the 10 ninjas completely own the 25 thugs. And considering Ra's is outnumbered, he will be on the defence so the thugs will be simply outmanoeuvred and dealt with.  Joker would attack hastily as 1) they are thugs 2) he has them outnumbered 2:5
And Ra's can take on Joker pretty easily so I think it's still an efficient victory for him.

@comicstooge: hmmm, I was gonna say Ra's stomps but then I saw prep. Joker spends his prep setting many traps, and using the thugs to lure Ra's into position. Ra's puts his ninjas in strategic positions, and the take out the thugs using ninja stars. Ra's then comes up behind Joker and decapitates him. Ra's takes this!