system
Given the following post, respond as if you're commenting on Reddit:
human
[General Superpowers] I have developed shapeshifting powers. I can't increase my mass though, and I can't change the chemicals that make up my body. What techniques can I perform with these limitations?
gpt
Really depends on how quick you can change.  If it's a slow change well then you don't have much of use other than pretending to be other people. Espionage can be useful but without the flash change ability if you get caught you lose the ability to get lost in a crowd. 

However with flash change you can get a few benefits other than getting lost in a crowd. 
Got an injury that's causes heavy bleeding? Shapeshift into a You that's not injured. This only works on superficial injuries though. 
Need a weapon? Shapeshift so that your forearm bone is petrifying from your palm as a shiv. 
Need to survive a fall. Shapeshift so your bones are all in one place. Bones break then re form them and your squishy insides should be fine.