Uh, Brawl has the same number of pokemon as Melee did...
Not to mention, Pokemon is a first party game, and it's the second to top selling franchise in the world.
But I can understand Falco and wolf. I'm pretty sure about 80% of the smash fanbase was thinking 'wtf' when we found out they were included. I think most people didn't believe Falco was returning, and that Krystal was a shoe-in.
Plus I'm sure even Knights had a better chance being in brawl than Knuckles or Tails did, since he at least his own game coming out. Actually pretty much any third party, save Capcom, had a better chance for a character than Knuckles or Tails. Look at Snake.