It's not that easy to start drawing prizes when you have to go from Horsea to Seadra to Kingdra and are barred from playing Rare Candy, Quick Ball, PlusPower, Pokedex, Warp Point, etc., which limits your ability to set up with Uxie and also leaves Horsea open to an easy and entirely unavoidable Poltergeist KO if the Gengar player opens the game. Even if the Kingdra player goes first, they would have to have a Horsea, Bebe's/Seadra and 3 water energy in hand to get a KO on Gastly on their next turn, which isn't impossible but considering how most Kingdra builds focus on getting set up with Uxie/mass trainers in addition to Claydol and don't play more than a couple Seadra, it becomes less likely to happen. It also means they would probably have to choose between getting the Seadra and getting a Claydol. Since Gastly can attack for no energy, the Gengar player could just sack a Gastly if they were going second and feared the turn 2 Seadra KO (and block trainers in the process) while getting their energy drop on a benched one that would come in immediately following the KO of their active, get Candied, get attached to, and Poltergeist for a likely OHKO on Seadra.