Thread:Flippmeister/@comment-12049730-20130906114341/@comment-8168904-20130909220614

300,000 Casino Coins, actually, and there's a 1.35% chance of getting a Shadow Mewtwo in the Game Corner. Getting Shiny Legendary birds, on the other hand, requires you to get 6 Shiny fire-, ice-, or electric-types and level them all up to level 100.

Normal Legendary birds are easier since you only have to level up normal fire-, ice-, or electric-types. That or abusing a glitch.