Duplicate items
To duplicate an item go to Viridian city and talk to the guy who was sick at the begining and talk to him.
Make sure the item you want to duplicate is the sixth item. Then go to Fuscia city surf down to the seafoam islands and surf along the shore (don't go on land) wait until you run into a Missingno, defeat it and you'll get alot of the items you duplicated.
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