Who should be my number six?

Question

Pokémon Diamond and Pearl are coming out on 4-22. I'm not much for "Gotta Catch 'Em All," so I decided to choose my party beforehand. I chose based on favorites. Naturally.

Riolu (pre Lucario)
Farfetch'd
Wingull
Piplup
Buizel

As you can see, I only have five. Also, I prefer Water types over everything (except Luvdisc). If I wanted, I could go through the entire game with just these, since they all have the capacity to learn attacks that can beat every type of creature I come across. But, I want a number six. Not including legendaries and creatures I'd have to load from other games, who should I choose?

www.serebii.net has info on all of the Pokémon

Answer 1

Since u LOVE water imma say...hmm..kinda hard but Mantyke or Evee then evolve to Glaceon :)....or if any pkmn i would say Roselia or Croagunk...

Answer 2

get GYARADOS