Eh, like I said, it's a cliche. And if we wanted, we could nerf them a bit, letting them gain stats over certain points (per gym badge?), or something.
The problem with, say, Ralts, is that its stats are ATROCIOUS until the Garde/Galle (Kirlia is basically level with Kakuna, stat-wise.)
And, uh, for the "one of each type", thing... some types don't really have options for starter-ish 'mon.
Like, Ice, which is usually late game. We've got, what, Vanilite and Swinub for choices? Swinub can't even fully evolve without breeding or move tutoring! And Dark. Which is literally Sandile or Deino, per 3 stage evos. Also Ghost, which has OP for every 3 stage choice (Gastly, Litwick, Honedge).