You first go to Vermilton city then go into a certain house and in ther will be a person who looks like a sailor. He will give you a old rod. Then use it next to water and what you catched will be a Magikarp. Catch it with a super ball then go to Lavender town if a Snorlax is blocking the way then take the Underground tunnel to Celadon city. Go to the department store there and by a
Poke flute. Go back to the place where the Snorlax appeared then play the Poke flute to wake the Snorlax up. It will get grumpy after it wakes up and you will have to battle it. Then after you defeat it go down on the path where the Snorlax was sleeping on. Then you will reach a small island with a house on it. Go in ti and there will be a person in it. He will say the size of your Magikarp then he will give you a net ball. Keep catching more Magikarps a keep doing the procedure. You will keep getting master balls. But don't show him the same Magikarp. He will say, "Hmm.. this is the same size as the old Magikarp you showed me..." So baecause of this he won't give you a net ball. Guarenteed!!