Help anyone? It's second time through.

Which Version?, And whats his team?

Get a blunt object. That's good for beating stuff. :3 Seriously, team and version.

I recommend he levels up all his pokemon to the MAX.
Or at least, like, 10 levels above the E4.

Its: HeartGold
He won't let me look at his team

Tell him to not suck and then level up his team up to at least 65.

I always just give all my money to my mom, and then just keep going through the Elite Four, which does give good EXP as you as you don't suck, and then eventually I'm strong enough to get to the champion and then I start using items.

Yes, hes a little dumb. He does know type stuff, so he uses Hippowdon on Bronzong forgetting its ability (hes not too good with IV's, natures, abilities and EV's and stuff) which is obviously fail. Then out comes Charizard (Kanto starter) and knocks him out. Out comes Slowbro... what to do? I know! Lets use Charizards Iron tail! He actully gets in some good damage before its done with curse. However, as you can see, he's not very logical

Level up his pokemon to 100 and if he still fails teach his Pokemon new moves but if he STILL fails confiscate his Pokemon and do what Quad said.

If your brother is still having trouble after being level 100, and after the two slaps to the face and the one lesson, tell him to start over.

Also, what are your brother's Pokémon?

SLAP, SLAP, TEACH, SLAP, KABLAM.
He smacked me hard... and loud... but hey. It didn't hurt. I came home early from school today. I traded his pokemon to me. Does that count as "confiscation"?

Yes it does. You can give it back to him once he memorizes the entire weakness/resistance chart.

Did he rare candy his team? That might be a problem.
If not, EDIT: tell him to do what Quadcentruo said. That should help.

Well, it IS a good idea, isn't it?

I'm sorry Rotom but your brother FAILS so hard!!

Seriously, tell us what his Pokémon are.