Ok first get pokemon around lv 50-60-70 and challage the elite id say have lots of full restores and full heals or go to the herb shop they have great healing stuff but its expensive soo if you wanna beat them easy get a fire,water,grass,eletric,ghost and any other there good for beating the league if you have strong pokemon go back there and train them by defeating league again because thats how i get my lvs to go faster and if your training lv 3s get a exp share and put it on one of them beat a pokemon elite member and get exp for other pokemon it worked for me on fire red and pokemon emerald