Yeah, that's how it is, Deathskully. It depends on what happens. For Vaporeon, you lose against Gary at the Lab when you first battle ; Jolteon is if you win at the lab and win west of Viridian City and Flareon is if you win at the lab and lose (or pass up) the battle west of Viridian City. :/
I usually got either Jolteon or Flareon.