Legendary Pokémon Appearances

When you have cleared the game and return to areas, there is a small chance that you will encounter various Legendary Pokémon. When you encounter these Pokémon, you will get into a boss fight and will have to defeat them in order to both proceed and attempt to obtain the Pokémon. You will note the encounters by the fact that the springboard that sends you to the boss room will be shiny. These Pokémon take the place of the boss for that level that time
Most of these appearances are not restricted to certain levels but in fact certain types ofs across all levels. These appearances are very rare, appearing for 5% of the boss battles, and may require numerous visits before it occurs. Some Pokémon have pre-requisites to appear, however all require you to defeat the Dark Rust and finish the story. The Pokémon are as follows