Here's why:
* They are not in the game: Pokemon Ranger features a different set of Pokemon than other mainline Pokemon games. These three legendary Pokemon were not included in the game's roster.
* They are plot-related: Entia is a powerful Pokemon that plays a significant role in the game's storyline. While you encounter it during the story, you can't capture it.
* They are rare: Swecune and Ricou are rare Pokemon in the mainline Pokemon games, and they were likely excluded from Pokemon Ranger for similar reasons.
If you're looking to capture legendary Pokemon in a Pokemon Ranger game, you might consider the following:
* Pokemon Ranger Shadows of Almia: This game features different legendary Pokemon, including Giratina, Heatran, and Cresselia.
* Other Pokemon games: If you're looking for Entia, Swecune, or Ricou, you'll need to play a mainline Pokemon game where they are available.
While you can't capture these Pokemon in Pokemon Ranger, the game offers a unique and engaging capture system that lets you encounter and befriend a variety of other Pokemon.