I've tried lead Jirachi and though he was effective, it just wasn't the same. If someone I battle has a Magnezone or Skarmory, I'll just give them a chance to set up when I try to hax Azelf with Iron Head. I could use Trick, but Scarfed Jirachi is so good at dealing damage with Iron Head, so I wouldn't want to give up a Choice Scarf without knowing what other pokemon my opponent has.
I didn't think about replacing Uxie with Vaporeon, though that would certainly help against my water-weakness, especially if Vaporeon knows HP (Electric). I did consider replacing Uxie with a Life Orb Celebi since it can easily OHKO the likes of Suicune with Leaf Storm, and kill off Scizor with HP (Fire).
Uxie's combination of Yawn + U-Turn is just too good to find a replacement for him. It's important that I know what pokemon my opponent has with a team like this, so that combo works really well in forcing switches. Not only that, but he's bulky enough to take hits so that I can switch an immediate counter in. And he learns Trick and SR, so he does a lot of tasks for my team.
Your suggestions are good, so I might try putting in Vaporeon for a test drive to see how it does. I'm not too sure what pokemon I can replace it with though, since like you said (and I agree), Uxie is the only pokemon that seems to be expandable at the moment.