You mean Prize Exchange? Note: "G" means Goldenrod Game Corner, "C" means Celadon Game Corner, and "B" means both Game Corners. HG means only in HeartGold and SS means only in SoulSilver.
Pokemon:
Abra (G)
Sandshrew (SS) (G)
Ekans (HG) (G)
Dratini (G)
Mr. Mime (C)
Eevee (C)
Porygon (C)
Items:
Silk Scarf (B)
Wide Lens (B)
Zoom Lens (B)
Metrenome (B)
TMs:
Substitute (G)
Swords Dance (G)
Rest (G)
Flamethrower (G)
Ice Beam (G)
Thunderbolt (G)
Endure (C)
Double Team (C)
Giga Impact (C)
Hidden Power (C)
Psychic (C)
Gyro Ball (C)
Remember, prizes differ depending on where you are: Goldenrod Game Corner or Celedon Game Corner