I am almost done the game. The only problem is lorelei of the elite four..

You have to go to Icefall Cave and beatr the Rockets.

You need to go into the Icefall Cave on Four Island. You will get the HM for Waterfall, climb the Waterfall and you will see Lorelei. She's being harassed by two Rocket Grunts. Beat them. They aren't difficult. Lorelei will return home, but not to the Elite Four. What you need to do is follow this part of the Gem quest.

Go to Six Island and go to the Pok�mon Center and get someone who knows Cut if you don't have someone who already knows it. Find your way to this cave that is sealed. Use the move Cut on the door and it will open. This area is known as the Dotted Hole. Enter Dotted Hole. The Sapphire Gem is here. To get to it, you need to reach the bottom by going down the holes. Go to the top one first, then the left, then the right and the bottom lastly. You will end up at the bottom, woot. Go get that gem! What the hell, a scientist takes it from you, yay. What's the upside to that? You get the last password to the Rocket Warehouse. Go to Five Island and go to Team Rocket's Warehouse. Now, enter it and beat everyone in your way. The puzzle is annoying to solve and is stupid, but once you reach the top, you find the Scientist and you need to battle him. He's not too hard because his Levels are around 47. Beat him and you'll have the Sapphire Gem. Woot. Back to One Island, give the Sapphire Gem to Celio. The Network Machine will be running, enabling you to Trade with Emerald, Sapphire, Ruby, XD and Colosseum. Now, you can go back to the Elite Four and battle them again. They're higher in level now and some Pok�mon have evolved. This gets crazy, bring lots of items to recover with! When you beat them, you can go into Cerulean Cave and catch Mewtwo.