MK's lead developer Ed Boon posted up some old assembler code from MK1 to Twitter earlier this week. I decided to hunt down that code snippet in the MAME debugger, since it should be "easy" to find in the disassembler.
Once I found it, I decided to use the debugger to tweak what animation plays when the move is executed. Just by changing one number on the processor, I could change how Sonya finished her move. Here are a few random animation tweaks to Sonya's Square Wave Punch, starting with the original move unedited.
My favorite is the final one, where it turns into a Square Wave KICK.