I think it depends, Patryk, if you want to sound colloquial or not. The answers given are fine, but they are all VERY informal. „Pulverized“ and „pounded“ is a bit over-the-top sounding to me. “Beaten up” is just another version of “beat”. Getting one’s bu@tt kicked, stomped, the cr@p kicked out of one, or being pulverized are super- informal and colloquial (you’re never going read anything like that or others on a police report for example). Bludgeoned means using a weapon/device was used to do the beating. Saying “it was a bloodbath” sounds like many people were killed, not just beaten. Bloodbath implies someone was killed. So it all depends on who your audience is. If you’re writing a police report or reporting for a newspaper or magazine you would not use any of these words, except for maybe bloodbath, but again, that would imply someone was killed. Instead, you might say someone was gravely assaulted, battered (which was mentioned and that’s fine) or just say “beaten and bloodied”. To say someone’s “a@@ was kicked” are a person got the “cr@p kicked of them” or “got stomped” sounds like a bunch of 12-year olds talking on a schoolyard talking. I guess if your audience is a bunch of 12-year olds, fine.

Pounded, pulverized, battered

“Beat up”

I agree with the others. You could also say, “he got his butt kicked, he got his brains beat out, he got stomped, he got the crap kicked out of him”. These expressions are more informal slang but in reality it’s the way we speak. Check out my teacher profile and let’s improve! www.italki.com/teacherhelpme

You could use "bludgeoned" but I think that means you used an object to hit the person. You might also say "it was a bloodbath" or "I beat him to a pulp."