Glitches

In an earlier version of PTD, after the x2 speed button was added, there was a glitch in the game where a pokemon that evolved with x2 speed turned on would evolve twice. For example, if dratini evolved at level 30 with x2 speed turned on, it would evolve into a level 30 dragonite instead of a level 30 dragonaire. These are different than hacked pokemon, as you could obtain them in the regular version of the game. As the glitch is gone and no more can be created, glitched versions of pokemon are rare.