I have heard that some people are having the problem of their Fight option disappearing after about 4 wild pokemon encounters. This happened to my brother yesterday. He was using Pokemon Black V4 and it was working fine, but then he downloaded V5 and I edited his Pokemon on Pokesav for him and when he went to play the game, his Fight option would disappear after 4 wild encounters. I can use the same Pokemon Black rom on my computer and it works just fine, although I haven't tried using pokesav since I updated to V5. What I did to fix this was load up Pokemon Black, then I went to the Battery folder where the .sav file is, then I deleted it and went on the Pokemon Black and saved the game so that it would created a new .sav file. This seems to have solved the problem. If any of you have this similar problem, have you used pokesav when you updated to Pokemon V5?
How is Nintendo supposed to check your card for the saves? Come on man. Probably an issue with the card and/or firmware.
I still have this problem, even after doing that save trick, and I haven't even used pokesav for B/W.