finally i got 6000gp with the wwe Smackdown vs. RAW 2007 achievement glitch:

To gain all 3 season achievements without doing the harder difficulties, first complete season mode by winning/defending title at wrestlemania. Save immediately after. Then continue as normal till you see the credits. The first unlock achievement should show. Now restart the 360 while on the credits and go back into season mode, change the difficulty to something different and view the credits again, this will unlock the other achievement. continue till you have done all 3. :)

kevinkiller out