Hey there, cool team you got here but it could do with a few changes. The first real problem I'm looking at is entry hazards, you must hate facing them, to fix this I would suggest you replace your current Jolteon with a
Rapid Spin+3 Attacks Starmie, this will give you fantastic bolt-beam coverage along with the insanely strong STAB Hydro Pump and will also make it so much more easy for your Salamence and Volcarona to wreck havoc thanks to the Rapid Spin support it gives to your team. Now the second change I would suggest is changing Salamence's Brick Break to
Fire Blast and the nature to
Naive because it just helps much more against the likes of Ferrothorn and Skarmory, Brick Break was hitting the likes of Chansey and Tyranitar hard but you can hit them hard enough with Earthquake and Outrage anyways, on Salamence Aerial Ace also seems like a move you just have there for the sake of it, I would suggest replacing it with
Dragon Claw so you don't need to lock yourself into Outrage if it is not needed. Now on Alakazam, Life Orb is cool Item but I would recommend you give
Focus Sash a try as the Focus Sash guarantees you attack once which won't always be possible with Life Orb and could turn out crucial, Alakazam already has great attacking stats so I would not worry about the drop in attacking power that much. Another change I would suggest on Alakazam is Hidden Power Ice over Charge Beam cause in my opinion something as frail like Alakazam can not really run Charge beam that well and
Hidden Power Ice gives you a great move to hit the likes of Landorus and Dragonite. Now the final change, your team need Stealth Rock, pretty much all teams need Stealth Rock because of the damage it can do to some of the most common offense threats in the meta game, for this I would suggest using a
Specially defensive Jirachi over Haxorus to serve as a great user of Stealth Rock while also give your team paralysis and wish support which is a really good thing on offensive teams, it also fixes a weakness you have to Tornadus-T under rain as it can pretty much OHKO/2HKO your entire team.Also I read about you not wanting to replace Jolteon but I really think Jolteon's slot was the best one for Starmie, give it a try, Starmie is pretty quick too, can stand up against Rain too but gives you better coverage and spin support.
Good Luck!