It is, therefore, inappropriate to insist that such knowledge become a requirement.
he's specifically having problems with a 3rd party plugin, which is external to the RPG Maker engine.
which is where the problem stands: right in the middle of connecting the engine, with the plugin.
the target system works by evaluating three statemens: scope of the skill (one/many), side of the effect (for enemy / for ally), and dead/alive.
if you want to target everyone but the user, then you have to modify "for_friend" so that it doesn't account for "11" which is the user.
since there's already a consideration for "11" itself, then you can take the 11 out of "for_friend", and it'll target any friendly except the user.
if you want to target *everyone else* except the user, then you have to remove the user from the final selection obtained after the evaluation of scope and side.... and that's more complex, you won't solve it with one fix to one instruction, and it can create problems with other selections such as item effects in the item window.
*that* is the coding you need to know.
if what I posted doesn't solve the problem out right, then you need to post the problem in Yanfly's page and ask for a fix for the script itself.