So far this is what i did.
Okay...that's not
super helpful because you're not showing the contents of the event where you're trying to actually use the plugin command. So we don't know if your syntax is correct at all.
But the trick here is that a common event has no way of knowing which battler was targeted by a skill. So you need to give it some point of reference.
For example:
1 - Give your skill an Add State at the top of its Effects list (any blank, dummy state)
2 - In the common event, you use a series of Conditional Branches
Conditional Branch -> Actor 1 Has dummy state
- type in the plugin command targeting actor 1
- remove dummy state from actor 1
Conditional Branch -> Actor 2 has dummy state
- type in the plugin command targeting actor 2
- remove dummy state from actor 2
etc.