What traversal skills does Celestis provide?

Neither ability is something you equip and then press a button for. Environmental traversal skills fire on their own: walk into a wall and the climb starts. Gliding begins from a jump off the ground, and you take the form of a gliding creature once you are in the air. So the practical effect of having Celestis is that vertical routes stop being walls and start being paths, and height you gain becomes distance you can cover on the way down.

There is a wrinkle in how the game picks who does the work. When you climb, fly or swim, it transforms you into your highest-tier capable Aniimo for that action automatically. What matters is that Celestis is in your roster and at the tier you think it is, not that you had it out at the time. Ledges and cliff faces are also how some wild eggs are reached, since getting to them requires an Aniimo at all.

Traversal Celestis does not cover

Climbing and gliding are two entries in a longer list. Twined traversal also includes dashing, flying, swimming and burrowing, and every Aniimo has its own distinct movement or exploration trait, so the rest of that list comes from other members of your roster. Emberpup's trait is Hustle, which moves you across the map quickly. Burrowing, from certain Aniimo, tunnels you underground and lets you interact with field objects down there.

Some obstacles are not a movement problem at all. Wooden barriers and trees need a fire-type Aniimo's field ability to burn through, and a lot of world puzzles are built around using fire that way. For flat open ground where no ability applies, the hoverboard covers distance faster than running. And certain open-world creatures hand out quests you cannot even start unless you are twined into that exact species, which is a reason to carry more than your climber.

Not settled: The highest-tier rule means Celestis is not guaranteed to be the one you become when you climb. Another climbing Aniimo at a higher tier takes over the action instead.