Hmmm... yeah, I remember this team. BIG need of a wall. First of all, you have more than enough physical attackers. 4 Physical Sweepers, 2 Special Sweepers. A lot of people like to with the [2*3] deal: 2 Physical Sweepers, 2 Special Sweepers, 2 Walls. Dodrio and Tauros can be dropped (although, you did pull a swift one on my with Dodrio). I highly suggest a Bulky Water-type wall, like Swampert or Milotic. It would work in perfect sync with Charizard and Jolteon to cover each other's weaknesses. Milotic makes a decent dual wall, so you may (but I stress may) be able to pull off just her, or someone similar. And since you have Charizard and Electivire, it covers the main weaknesses of Electric and Grass moves. Cresselia could work in the same way, but I'm not sure how keen you are on using leggies.
But if you run that, I'd also suggest a Ghost type, or a really strong Steel type to cover anyone who wants to Explode on her, making way for your team to get sweeped. Dusknoir could work well with that, or even Spiritomb.
A nice Ground Pokemon, like Donphan, or even Skarmory would also benefit this team, because an Earthquake/Stone Edge combo is just asking to pwn. If something like Tyranitar got a Dragon Dance or two in, you may be toast no matter what.
Just my 2cents!