I didn't know every Sinnoh starter was dual-type. Interesting.
I like starters where the Basic and Stage 1 Pokemon are single-type and the final starter is dual type. Like the Charmander line, where Charizard is Fire/Dragon. For some reason I always thought that Feraligatr was Water/Dark... maybe because it learns bite?
Charizard is not Fire/Dragon... It's Fire/Flying.... Have you checked any of the Starters' actual type? I think you're judging more on appearance than fact.