Can all creatures be caught in the wild?

What that rules out matters more than what it confirms. There is no roster of creatures locked behind a gacha pull, a summon banner or a shop page. If you have seen a creature in Aniimo, the route to owning it runs through the open world and through you going and getting it.

Capture is an activity rather than a menu confirmation. You deploy Anipods, set traps, sneak up on things, and use the terrain around the creature to your advantage. Which approach works is a question about the specific creature and the ground you are standing on, so the skill you build is in reading an encounter, not in grinding currency to buy an outcome.

Legendary tokens follow the same logic. They come from exploring the world, from catching, and from pushing through the main story, so the things you would expect to sit behind a paywall in a game like this are instead sitting behind play. That makes a long session of open-world wandering the core loop rather than a side activity. Time spent out in the world is time spent acquiring both the creatures and the things that matter around them.