Developer Mode was added in the 0.0.8 patch, allowing players to change the characters stats for balancing purposes.

In the 0.0.8 patch was the ability to go into a file and edit frame data, damage, and knockback angles among other things for any character.

After going into Versus Options and turning Developer Mode on, you can see the changes you have made take effect in versus or practice mode. Pressing F3 will reload new changes in case you have made any during the battle.