I was battling my friend and he had three base blastoises and two dark ones,
but he said since it says "Dark" in the name he can have four of each.  I say
he can't. Who's right?

You know, as many of these as I get where the "friend" is wrong, for once the person writing the letter is wrong.  Blastoise and Dark Blastoise are two unique names, and thus can have 4 of each in a deck.  Another example is Cool Porygon.  Because of the slight change in name, you COULD have 4 Porygons and 4 Cool Porygons in the same deck.

Scott