How do I select one enemy from a group of foes to attack?

Heya, I'm making a RPG/Point and Click hydrid game which I been working on since... 2018 I think.

In the battle format, which is basically like Paper Mario/ Mario & Luigi's, normal battles could have a small group of foes say... a small gang of dandelion monsters or some bullies.

I want it so you have to select a target (Some attacks affect them all) before you take action.

You can have instance variables on the enemy and when clicked you change the value of it so you know that is the targeted one, variable could be targeted=yes/no. Then when you perform the attack it is done on the instance where the variable is set.