A while into the story, you will learn that Trico can catch you with his tail. This is a sripted part of the story. Afterward, whenever you are on Trico above the abyss (like climbing a tower) you can grind this by letting go of Trico and grabbing his tail. The game will go into slow motion as you attempt to grab Trico's tail, this indicates that you are doing the technique correctly.
Here is a video guide with English commentary!
Here is playlist of guides for this game!
https://www.youtube.com/playlist?list=PL-HeW6XkKdULD7WVqUHgB...