Fly back home to New Bark Town and talk to Professor Elm. He'll give you 1 Master Ball. It's 100% capable of capturing any wild Pokemon. Even Legendaries. Now fly to Ecruteak and head into the Kimono House above the Center. Once inside you will automatically fight all 5 sisters one at a time. They each have 1 lvl 38 Eevee evolution. Once you beat them you'll get the Tide Bell (again in SS) and it's time to go get your first Legendary.
Pokemon League - Kimono
REQUIREMENTS: Silver Wing from Radio Manager in Goldenrod City (Story) & Tide Bell from Kimono Sisters in Eructeak City (Story).
ABILITIES NEEDED: Surf & Whirlpool (Flash very helpful)
Get to Olivine City and then go left to Route 40 followed by Surfing south to Route 41. Use Whirlpool to get to the middle right island. Walk around to the left side and then Surf to the bottom and to the Cave Entrance. You are now at Whirl Islands. Once inside use Flash (Not required but makes moving around so much easier. If you didn't get it at Sprout Tower you can buy it on the cheap at the Goldenrod Department Store.) Work your way right dropping from ledge to ledge until you get to the ladder going down. Go left and talk to the old Monk. He will check your Silver Wing and let you continue. Go down the slope to the last entrance and enter. The Kimono Sisters will be there and they will take back the Tide Bell. Swim over to Lugia and work it.
Legendary Pokemon - Lugia
Before moving on you will need Surf, Strength, and Waterfall. Then Surf right to Route 27 from your home town of New Bark Town. Once you clear the old man since you either captured or eliminated Lugia you can enter the Falls. Surf to and then up the Waterfall and down the other side to continue on Route 27. Continue through 27 to 26 until you finally hit the gatehouse. Right before the Gatehouse is a home where you can heal your Pokemon. At the Gatehouse you'll be checked for all 8 badges and then allowed through.
Work your way through the first area till you get to the first boulder and push it up out of your way. Then up the stairs and over the bridge and down the left side until you get to the ladder. Now go down and right till you hit the next ladder. There will be a hole right where you come off the ladder so drop back down. Head down the path and the push the boulder out of the way and go up the middle stairs to the next ladder. Skip the first hole and continue on until you see 2 holes. Drop down the bottom one. Now just keep on the path until you meet to fight your Rival again.
lvl 36 Sneasel, lvl 40 Fergaligatr, lvl 38 Golbat, lvl 37 Magneton, lvl 37 Kadabra, & lvl 37 Haunter vs. lvl 37 Ampharos, lvl 46 Typhlosion, & lvl 45 Dragonair
Then head on out and into the Indigo Plateau and the Pokemon League.
Pokemon League - Getting To The 4
Heal and buy some Full Restores and Status Healers. The following battle is 5 Trainers in a ROW. You can use items between but not heal or buy anything. It's a total of 26 Pokemon.
As long as you can beat the first of the Elite 4 you'll end up positive for EXP and Money. These 5 Trainers are GREAT for EXP. Just keep blasting away at them.
lvl 40 Xatu, lvl 41 Slowbro, lvl 41 Jynx, lvl 41 Exeggutor, & lvl 42 Xatu vs. lvl 62 Typhlosion & lvl 53 Ampharos
lvl 40 Ariados, lvl 43 Forrestress, lvl 42 Muk, lvl 44 Crobat & lvl Venomoth vs. lvl 63 Typhlosion
lvl 42 Hitmontop, lvl 43 Onix, lvl 45 Machamp, lvl 42 Hitmonchan & lvl Hitmonlee vs. lvl 56 Lugia & lvl 63 Typhlosion
lvl 42 Umbreon, lvl 47 Houndoom, lvl 45 Gengar, lvl 42 Vileplume, & lvl 44 Murkrow vs. lvl 63 Typholsion
That is the full list of Pokemon the 4 will bring to the table. I suggest you look them up on SuperCheats.com's Pokedex to learn their weaknesses. My Pokemon might seem WAY over leved and to an extent they are. BUT, this is a great place to suck up EXP and the higher you are now the easier the last half of the game will be.
Pokemon League - Elite 4
lvl 46 Gyarados, lvl 50 Dragonite, lvl 48 Aerodactyl, lvl 49 Dragonite, lvl 49 Dragonite & lvl 48 Charizard vs. lvl 53 Ampharos & lvl 56 Lugia
Lance's Dragonites LOVE Thunder Wave so be prepared to heal Paralyze and he used 3 Full Restores in my battle so have some of your own to match. Afterwards you will be taken to the Hall of Fame and be inducted along with the Pokemon you have in your party. Watch the end credits and then load your save to start the next section.
Pokemon League - Champion