Beat up as a transitive verb means: "to give a severe beating to, etc."
Example: I got beaten up by thugs on my way home.
Also, Cambridge says:
Beat up: to hurt someone badly by hitting or kicking them repeatedly:
Example: He claims he was beaten up by the police.
Now, let's say someone is bothering a bully who doesn't tend to fight them. He just wants to warn and threaten the guy to go away, otherwise he would beat them severely.
Which one of the following sentences would indicate the message that the bully needs to convey to the annoying guy:
1- Get out of here, or you'll get beaten up.
2- Get out of here, or you'll get beaten badly.
I think both sentences indicate the same meaning and both are completely natural. But I had to inquire about it.
Best Answer
You beat someone up. You beat someone up badly.
You would not say to someone: Get out of here, or you will get beaten (up) badly [by me].
You would say: Get out of here, or I will beat you up!
That is what you tell someone else: He got badly beaten (up) by those guys.