That is a really excellent part of a team. Starmie is one of the best pokemon in the game. Regirock, though, sucks. You should replace it with a better pokemon, such as Rhydon(Holding a Quick Claw). As for the other members of your team, I suggest a Shiftry for a grass pokemon. Keep it as a Nuzleaf until lv.49(extrasensory) then evolve it. You should then teach it giga drain, razor wind, and a defensive move. For an electric type, I strongly suggest a Magneton. It has a good defense, and an INSAINE special attack.(Nature-Modest[+sp.atk -attack]) Finally, as a finisher, normally I would suggest a dragon pokemon like Salamence or Flygon, but you already have a weakness to ice. You should add a pokemon such as Torkoal to your party. You already have a weakness to water, but Torkoal has extremely high defensive stats, so it should be okay. Just a little insight.