Hello. With the 2.0 patch, many ninjas have been changed. You can find more about the changes in strategy section pinned list.
http://forum.naruto.oasgames.com/en/forum.php?mod=forumdisplay&fid=36
Tobi was nerfed this patch. He no longer inflict knockdown on his mystery, dodge lesser (in my observation so far), and does not revive any longer. He however, gives you 20 yummy chakra each round.