I would recommend that you use the time flutes on strong pokemon. The weak ones such as quilava, croconaw, and others that aren't legendary or powerful, can just be purified fast by either walking around, using scents, day care, or battles. Use the time flute on either Metagross, Tyranitar, or the three ledgenday dogs; Suicune, Entei, and Raikou. (I don't care about spelling.) I'd recommend Entei. I have him as my 3rd strongest pokemon. I have 2 Scizors that I traded that are both level 100.