2 Best bets are:
Google it and see.
Or, try watching MUGEN videos on YouTube and see if they say about a source where you can download from.
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EDIT: http://www.g4g.it/2007/11/05/naruto-battle-arena-2-versions-mugen/
Chat with our AI personalities
you can get naruto mugen chars and a lot of other chars in mugencharacters.ucoz.com Believe me, it's an awesome website^^
hokage546
down up then attack
Press down + E twice
Getsuga Tensho, Rasengan, and Shadow Clone jutsu? I think that is it. My boyfriend is and Naruto/Bleach fan. So i called him and tried to answer this.