Used bcm
 

Can a used bcm be put in a.n ion 2? Can it be flashed?

Technically no.
it is flashed to the vin, which is also mated to the ecm and gauge cluster.

Now, if you were to say go to the junk yard. Find one with the same features, auto to auto or manual to manual etc

You could get the ecm, bcm, and gauge cluster and it should work. You may need the ignition cylinder too. I don't completwly remember.