The move has 40 PP, and does not have a rating for Power.
Until it learns Tackle, Magikarp must rely on it as its only move, and must be leveled up without fighting on its own.
Soon after the release of Pokemon Red/Blue, a rumor sprung up about Splash. According to the rumour, raising a Magikarp to a high level (around Lv60+) would make Splash actually damage a single foe: Kadabra.
Another rumor is that Splash made the apperance of rare Pokemon actually increase the more you used it. This has yet to be proven true or false.