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Tepig is the best, but all three are outclassed, which is pretty ironic considering the starters are supposed to be your most dependable Pokémon.
The only one that sort of has a niche is Oshawott, but it's just a bad Feraligatr with Megahorn. Get a Jellicent, or do like me, complete the game without any Water Pokémon. They're not needed at all.