As a service to easily impressionable kids who may be reading this, let's do something out of the ordinary and apply a practical approach to the entire situation.
Your opponent can draw six prizes during the course of the game. This is because by the very basics of the game, only six prizes can be drawn. A short breakdown of them, modified so that it would be like a better setup for Gyrados, follows.
Prize 1: Most likely a starter of yours.
Prize 2: Ideally, your first Gyrados.
Prize 3: A second Gyrados, which you most likely used one of your four Pokemon Rescues to get fully recovered.
Prize 4: A third Gyrados, which you most likely used a second of your four Pokemon Rescues to get fully recovered
Prize 5: A fourth Gyrados, which you most likely used a third of your four Pokemon Rescues to get fully recovered.
Prize 6: Pretty much anything, but hopefully a Gyrados.
Now, after Prize 5, Gyrados deck most likely still has one Pokemon Rescue, a TSD or two, or any number of things left to get the last Gyrados. Of course, if the opponent gets another prize by any other means during this example (by killing a Crobat for example), you won't even need a fifth Gyrados, as your opponent will have drawn his last prize on your fourth Gyrados.
I hope that was simple enough to understand. Shen is absolutely, 100% correct. Calisupra is absolutely, 100% wrong. Going back to what I said earlier, your opponent can only draw six prizes on you. Why in the heck would you want to put enough recovery cards to survive infinitely? You DO NOT need Floatsel in Gyrados. If you're determined to put something interesting in the deck, put Luxray X or something to further increase the deck's speed, or find some other hole to fill. Don't put in a 1-1 tech that you'll never conceivably need during the course of the game.