There is always a way to unlock content via memory manipulation. This method is more difficult to do but when it comes down to detection it is way safer than public pasta ware, to brief you in on how it could be done here are a few steps you can take to try and achieve that:
1. Make sure you know what you're dealing with memory access requires a bypass.
2. Go to a character screen pick one character, scan for unknown initial value in CE (4 bytes recommended) change the character and do a next scan of changed value, repeat this step till you have narrowed the list down to 1 - 20 addresses.
3. Attach a debugger to one of the results and look through the code to make sure you know what makes it tick.
4. If you found a way to unlock all characters implement it into your bypass and enjoy the result.
these steps are universal and could work for almost any game.