Acrobatics is composed of three separate Subskills; these are Climbing, Dodging*, and Gymnastics*.
(For details, see the white book on pages 74-75 or Blood of Heroes.)
It's possible to use the Climbing Subskill Untrained, but the results will never be spectacular.
In addition to determining the skill of the attempt in difficult circumstances, Climbing maxes out at 3 APs of distance in a four-second single phase unless the character also has the Superspeed power or another relevant travel power.
Dodging is not a Skill that the player rolls! Instead, the player adds their APs of this Skill to their OV when someone else is rolling to do something to them. Remember that this Subskill cannot be used "Untrained" to get this advantage, and see more information in the detailed rules for Dodge.
An Olympic gymnast like Trickshot will probably possess 6 or 7 APs of the Gymnastics Subskill, which covers rolls, tumbles, flips, juggling, balancing on a narrow surface, body contortion and balancing in unusual positions, parkour, rope climbing, flying rings, ribbon dance, and vaulting. This is also a Subskill that cannot default to the Attribute for an untrained Character. Trickshot spent a staggering amount of hours each day throughout his childhood and early adulthood in developing the proficiency he now uses to save the day.