Acrobatics

Anything that the GM would consider acrobatic, as in something that would require physical dexterity to achieve that doesn't fit other types of action sub-types, is considered a Special Movement or its own kind of action.  This could be something as simple as flipping over an opponent in battle to get behind them, for example.  If the GM considers a specific action or movement an acrobatic feat, then the GM may set the challenge rating of said feat and the character rolls Dexterity against it.