Gyarados - 21/98 - Alternate Holo - Promo (Cosmos Holo) from Pokemon Miscellaneous Promos, available at 401 Games Canada.

• Rarity: Holo Rare
• Finish: Holofoil
• Artist: TOKIYA
• Card Text:
  Theta Double — This Pokémon may have up to 2 Pokémon Tool cards attached to it.
  [2] Full Retaliation (30+)
  This attack does 30 more damage for each damage counter on each of your Benched Magikarp.
  [2WW] Thrash (100+)
  Flip a coin. If heads, this attack does 30 more damage. If tails, this Pokémon does 30 damage to itself.