Watching that video of kids fighting made me realize that there is no way I could or ever will fight anyone. I just can't/ couldn't ever do it for some reason.
I'm going to say don't fight him, because literally it's a lose-lose situation, like other people said. So personally if I were you, I wouldn't.
Hell, I had plenty of times where I should have kicked a few kids asses but I never did. I wish I did though... story time so you can understand why I wish I did:
Story#1:
Right now I'm 6'3" 195 pounds, so I'm finally thinning out. I used to be pretty chubby/fat and I have been all my life. I've also always been a great amount taller than other kids too.
Back in middle school there were these two punk/jerk kids on my bus. I was sitting by myself in the very back seat of the bus one day, in the single seat. One of the jerk kids gets on (I don't remember details it was so long ago) and he starts telling me he wants the single seat. I was like, "well I was kind of sitting here before you". He starts calling out "oh fatass needs the single seat to give himself more room", some kids started laughing. At that point I was going to just give him the seat so that he would shut up, because it literally wasn't a big deal. So I stood up and was like "alright fine you can have it" Then he was like "oh no now you gotta stand up for yourself" as if this turned into some time for a teaching lesson, and he pushed me back into the seat. So then his punk buddy gets on the bus and they both sit in front of me and I can hear them talking about how I wouldn't give up the seat at first, or something. So then one kid turns around and punches me (kinda lightly) in the face. So I just turned away and started to look out the window. Then his friend kind of pushes me over and sits down in the single seat next to me. So I look at him and he does that "head butt" thing to the face which hurt like a bitch. So I was getting pretty annoyed at this point and I tried to push my way out to go up to the front of the bus, or just try to get away from these jerks. The kid in front of me takes his thumb, and jabs it into my eye. I put my hand over my watering eye and kept trying to push my way through and away from these two kids. They started yelling at me to "stand up for myself", while punching me in the face a bunch of times. I finally ended up getting through in time to get off at my stop though.
I don't know how the bus driver didn't see ANY of this, she never really cared about anything in general though.
I've also never told anyone that story either. I got off the bus with a bloody nose and stuff and just told my parents "I don't know how it happened, it was just a random bloody nose".
For about a year after I got called "the kid who can't even stand up for himself".
Sorry that was a long, stupid story. I just wanted to say that, I wish I would've just beat the living shit out of those kids. I didn't though, and if you just ignore this little situation you have, nothing bad is going to happen from it.
Story #2:
A few years ago in freshman and sophomore year in highschool, in gym class I got made fun of by 3 kids constantly for being "fat, and stupid and a waste of space" It went on for half a year freshman year. Then a quarter of a year sophomore year. My gym teacher overheard the kids during sophomore year though and the kids got sent to the principals office. She asked me how long it had been going on for, and when I told her... I think they got into some pretty big trouble. I didn't see them in class for a few days after that. So at first I wish I could've kicked their asses too. Although I'm sure whatever they had to sit through for those few days was a lot worse. Haha.
Basically OP: don't beat them up, it won't accomplish anything. I didn't beat anyone up even when I should have, and I turned out fine and didn't die. Haha