In Metropolis, if you get through the whole level without beating a single enemy and talk to the Inventor Droid at the end, she'll say "I've Successfully developed a super powerup here Spyro... knock off just a few more enemies and you can be the first ever to use it." This dialogue isn't normally available to see or hear because the power up only requires one enemy to be defeated to work and there are enemy pigs that self destruct when you get close enough to them.