Board Thread:Pokemon Arena X - Discussion/@comment-5398529-20131112013835/@comment-5537612-20131112160727

I keep on forgetting this is part single-player.

Agreeing with poke here. Legendaries could be encounterable multiple times (if they are in a dungeon you need to find a key item first, in case of the weather trio an orb). Defeating it once will yield it's sticker, but if you already have the sticker (inventory or otherwise) you won't be able to obtain that sticker anymore. If the legendary happens to be shiny, it will drop a shiny sticker. Normal stickers to not impede the dropping of shiny stickers, and vice versa.

Roaming legendaries need to be unlocked first before they can be encountered (for the birds, this could mean meeting them at the top of a mountain, at which point they will scatter). You will need a Magic Map in order to track them down (special item can be bought blgughsgh). They could continue roaming during battle, leading to a Monster Hunter-esque scenario, where you have to chase it from location to location.