Shiny Pokémon are much rarer versions of Normal Pokémon that have a different color scheme and gain 50% more EXP than Normal Pokémon.
They are characterized by a color scheme that differs from their Normal coloration, as well as a sparkle in their sprite. The difference varies from drastic, e.g. Shiny Gyarados, to more moderate, e.g. Shiny Pikachu, to almost unnoticable, e.g. Shiny Venonat.
Shiny Pokémon have a 1/8000 chance or 0.000125% chance of appearing in the wild in PTD 1 and 2. In the real Pokémon games, the chances of encountering a Shiny Pokémon in the wild are 1/8192 or 0.00012207031% chance, but in X and Y the chances are 1/4096 or 0.00024414062% chance. Shiny Pokémon ALWAYS have a red life bar in PTD 1 and 2, so you can catch them via Pokéball without having to lower their HP, also, preventing accidental KO's. An alert will appear the instant a Shiny Pokémon appears. When it appears, the game pauses until you click on the screen. The screen reverts the play speed back down to x1 to help you ensure that you don't defeat the Shiny.
Shiny Pokémon by Update (PTD 1)
Role in the Game
Something of a hidden extra, Shiny Pokémon are not necessary a part of the game. Due to their rarity, in fact, it would be easy for a player to not encounter any. However, as they are typically the rewards for deciphering Mystery Gift clues and beating Challenge Mode levels, it is not terribly difficult to obtain at least a few. Shiny Pokémon are inspired by the creatures of the same name in Nintendo's original games which both feature special aesthetic effects. In the original games, unlike the Tower Defense version, they gain no extra experience. As with the Nintendo games, Shiny Pokémon are especially valuable to collectors and others who see a "coolness factor" in their rarity and are as such great bargaining chips in trades.