Backyard Wrestling 2: There Goes the Neighborhood Cheats

Complete career mode with your career saved in the first save slot (the top of the list). Now start a new career, saved in the second slot. After you're in career mode, select Exit Career to go back to the career selection screen. The game will autosave your new career as you exit. Now delete your first career, the one you completed. This will move your new career from the second save slot to the first. Load/Play that career, and you'll see that you now have the follow stats from your original saved career: Overall & Tier 1-3 Win/Loss, Win Percentage, and Opponents Seen.