A couple things. 1) what is the red square and green square that the user is to select? 2) on that initial GetPointerPressed() check you are checking for sprite hit. You specify red sprite as 11 and green sprite as 12. What are these sprites? I'm not seeing those sprites as being created so these sprites are never registering as being hit so the global variable localSprite isn't getting set to either Main_Host or Main_Client sprites so on line 173 where you are assigning originalx# and originaly# to the localSprite's X and Y it is looking for the X and Y position of the sprite id 0 as 0 is what is assigned to localSprite's variable. That is what is causing the Error.
I don't have a true fix as I'm not really sure what is needing to be selected. You do need to do some kind of condition if some other sprite is hit as you will get that sprite 0 error if user clicks any other sprite.
What I did to test things is where you have if(hit=11) I changed it to if(hit = Main_Host) and you code if(hit=12) changed to if(hit=Main_Client) then when the characters are selected you won't get that error message and you can move around the character that was selected. The problem lies in that you don't do any detection of other sprites being selected and when that occurs you will get that sprite 0 error. And unfortunately not sure how to resolve the issue but you may check at that area in you code as that is where the problems are.
