I'm trying to beat the elite four how do I beat them easy?

You should really balance out your team and levels, because all you need to do is have a balanced team with good levels and movesets.

I recommend using Charizard if you have it, or a Machoke/Machamp for Lorelei. You will have an easy time with it just using Flamethrower and Brick Break. For Bruno, a Flying type like Fearow with a Choice Band will tremendously help. A back-up Water-type like Starmie will take care of his two Onix's.

For Agatha, a ghost type of your own like Haunter or Gengar will be your best bet. A psychic type will also do well because everything is Poison.

For Lance, if you're using a Starmie, teach it Ice Beam and Thunderbolt (Those are two of it's competitive moves) and that's all you'll need. Surf will be there for Aerodactyl too.

I can't tell you what to do for Gary, because I don't know what your Starter is. Make sure you hit the 60 range to make it really easy.