THE COUNTER GLITCH!
If you've experienced it, I feel your pain! Mine was reset twice and I had to do 500+ boss wins before I got this achievement. Anyways, it seems that anytime you are playing and the phone is interrupted,( you receive a call or text, low Batt. msg appears, etc.) the counter for your boss wins resets to zero. The good news is you CAN retrieve your wins if your careful and immediately quit to your home screen when you notice the reset counter. If you continue to play, the game will save over making it impossible to retrieve your wins. What I did was check my wins counter after EVERY playthrough. I would start from lvl 1 and play through to level 3 or 4 and then loose all my balls and end the game. I would suggest not quitting out and just loosing all your balls and letting the game register the wins. After each playthrough I checked my counter and I'm glad I did because around 200 wins my battery went low and the low batt msg appeared. Sure enough when I checked my counter it was reset. If you see your counter is reset, just hit the windows button to get back to your home screen and reload the game. As long as you caught it and did not play after it reset, you'll see your wins have been restored upon reloading the game. This achievement is annoying enough without getting reset so good luck TAers and keep a close eye on that counter!