Instructions
Go to the Tin Tower on the eastern side of Ecruteak City in the north of the Johto region and head inside.
Defeat the three Sages on the bottom floor of the tower. Each has a Level 32 Noctowl, which you can beat using Rock, Electric or Ice-type attacks. Sage Gaju has a Level 32 Flareon, which is weak against Ground, Rock and Water-type Pokemon. Sage Masa has a Level 32 Jolteon, which is weak against Ground-type attacks, and Sage Koji has a Level 32 Vaporeon, which you can beat with Grass and Electric-types.
Go up the stairs at the back of the room and climb up to the third floor. To cross the one-way jumping tiles, go one to the right, then walk forward and take two jumps to the left. Walk around the central spire of the tower and take two jumps to the left followed by five jumps to the right and you will reach the stairs to the next floor.
Cross the fourth floor by going left as soon as you enter the room across two platforms, then down one to the middle of the area. Go straight ahead across two platforms to reach the next set of stairs.
Go forward onto the platforms and jump to the right twice. Jump down, then twice to the left, then down again three more times. Go one space right then two steps down, followed by two jumps to the right and one down to get to the stairs to the sixth floor.
Walk straight across to the middle of the tower, turn right and go up and to the left. Jump down two platforms and continue up to the stairs. Climb up to the seventh floor.
Head to the right, ignoring the first red teleport pad on the ground, and take two jumps across the platforms to the right. Jump down four times and use the teleporter on the left. Walk straight ahead to the next teleport platform, then to the left and down to the next one. Go around the center pillar and left to the final teleporter which will take you to the stairs.
Head up the final flight of stairs to the roof of the tower, where you can summon the Legendary Pokemon Suicune and Ho-Oh.