Instructions
Walk south from Viridian City or surf north from Cinnabar Island to reach Pallet Town. Enter Daisy Oak's house.
Talk to Daisy between 3 p.m. and 4 p.m. She offers to massage your Pokemon. Select any Pokemon for her to massage. This increases the Pokemon's happiness.
Take the Pokemon to Daisy for four more massages. Daisy gives one massage per day between 3 p.m. and 4 p.m. You do not need to go to Daisy four days in a row for the massages to work. After it gets five massages, the Pokemon has maximum happiness.
Visit Daisy between 3 p.m. and 4 p.m. with the happy Pokemon in your team. When she sees it, she gives you Blue's phone number.
Call Blue on a Sunday evening to set up a rematch. When he accepts, meet him at the Saffron City Fighting Dojo for the battle.