Deoxys, the rare multi-formed Pokémon found in a 20 Floored Dungeon with nothing but Deoxys shadows in has its own mechanic whenever you go into a new floor of a dungeon
When you go into a dungeon, Deoxys will randomly change into any one of his forms, such as the defense form. Like in the game the forms alter it's stats although not as big as in the game
It also changes when you move between floors allowing you to be all 4 forms inside a dungeon
However you cannot manually change it or decide what form you are so it's pot luck.
Unfortunately in dungeons where you are temporarily reduced to Level 1, as well as when in town, Deoxys sticks in it's Normal form.

 
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