I've read stories where legendary Pokémon were treated merely like legends, with them being extremely rare and barely showing up but I've also read stories where legendary Pokémon were more prominent going as far to be controlled by other characters and appear in flesh quite often.
How do you handle these type of Pokémon?
They're powerful creatures of unique capabilities, hence the fact they're referred to as legends. Do you treat these Pokémon simply as myths and legends or do you actually have them show up when the plot calls for it. In addition, which approach on legendary Pokémon do you prefer?