Can i ise mind control and this guy to scfew with my opponents game..as in mind control there thor..and replace him with tanarus?..

You should really ask this in the Rules section, but I think if you have the appropriate figure on your side board and the conditions are met, you could do it.

actually the wording is "Give this character a close or ranged combat action (minimum range value 4) that deals no damage. A successfully hit target becomes friendly to your force. Each target hit may be assigned one action as a free action, immediately after which the target becomes an opposing character again. Deal this character 1 unavoidable damage if the successfully hit targets’ combined point value is 150 points or more" so you can't give a mind controlled character a power action so you can't do that

Ok so i think i know what your getting at but i'd look at how you worded that it could be taken many ways..if i took that literal then i'd be wondering why so many mind controlled characters have been able to use charge, hypersonic speed barrier and so on those are power actions..i was always under the assumption m/c operated kinda like a give this character a power, close combat or move action
as a free action..i know what the wording is just don't get the complete logic i can m/c someone and give them a power action as a free action to use smoke cloud as it were but here with this power it's different..

Can he replace the mighty thorr with his trait? the mighty thorr real name is thor odinson. I don't think it counts but I really hope it does.

No, the trait specifically says the other character has to be named Thor... Mighty Thor is a different name.

I think you could do it. Problem is, at the end of the M/C, the character goes back to the other player's control. All you'd be doing is giving them Tanarus.

I think your missing the point..ask yourself how you'd feel if you brought the 275 pt version of thor from this set with indomitable and power cosmic..and your opponent forced you to play the rest of the game as this guy...you'd be mortofied...as it happens i know now it can't be done anyway..a little rule designed to stop just this kind of abuse lol in order to replace a character it must have been friendly to your force from the beginning of the game...damm lol tht would of been nice..i suppose it makes sense mind control isn't always mind reading..cant force civilians to ae into superhuman alter ego if you don't know who they a.e. into right