my opinion?  I would  use vaporeon as a sixth pokemon you'll want it to take down blaine. i think vulpix is a  pretty good choice, but  the only thing about kadabra is that it's defenses are less than desirable you'll find yourself loosing a lot of hit points to physical based attacks  like double edge.  

Pikachu is overrated. Go Vaporeon and Vulpix.

Whatever you do keep Kadabra. Phsycic types will win you the game. Also try to evolve that Pikachu. Raichu is just a better Pokemon and I don't know were you would get a light ball for Pikachu. Also as for Vaporeon vs Dragonair...ehh depends you can get Vaporeon sooner but Dragonair will become Dragonite. Maybe you could just replace Speaorw with Dragonair and still use Vaporeon. Also you should evolve Eevee as soon as you get it unless there is a certain move you want it to know.

Rate: Needs more Dragons,

Pro Tip: Catch em.