Does potency change the probability of TM reducing on the enemy? And does tenacity change the chances to resist to TM reducing on allies? Or do efficiency and tenacity only affect penalties over the head of the characters? I mean to Jyn Erso's attack "Rebel Counterattack": if I increase her potency, do I increase also her chances to reduce enemy's TM?
In addition to what those above me said, it is also noteworthy to point out that if an enemy has Tenacity Up, they will resist all TM reduction (unless the reduction is stated as "unable to be resisted".)