Legendary Pokémon are typically exclusive to the main series Pokémon games. They are often rare and powerful Pokémon, and they play a significant role in the storyline of those games.
Pokémon Ranger games focus on a different gameplay style, centered around capturing Pokémon and using their abilities to solve puzzles and complete missions. The game features a wide variety of common and rare Pokémon, but Legendary Pokémon are not part of the game's roster.