Your item is useless, Drizzle is everlasting unless confronted by another weather, or something like Air Lock / Cloud Nine. This being the case, replace that for Lefties.
Being a more bulky Kyogre use Scald instead of Hydro Pump.
Also, don't try to over complicate EVs. 252 HP / 60 Def / 196 Sp Atk works great here.
Go ahead and don't try making this thing bulky. It's doesn't work super well.
Jolly nature w/ 252 Atk / 252 Spd / 4 HP works great.
Now here's something really cool I found, try running a Sharp Beak. This will make you have a pretty super charged Brave Bird. Replace Recover with Substitute. This makes Ho-oh almost like a Staraptor for use in Ubers.
I highly disreccomend Arceus-Electric. Just go for the standard normal type Arceus.
EVs: 252 HP / 252 ATK / 4 Spd
Dragon Claw / Earthquake
I have a pokemon later on in the team that I think needs to be completely replaced, but I'll get to that in a minute.
I have to give Smogon credit for having one of the most effective Mixed-quaza sets I've ever used.
Rayquaza@Life Orb / Lum Berry
Ability: Air Lock
EVs: 4 HP / 252 Sp Atk / 252 Spd
I like Life orb, personally. This is a great wall breaker you can use.
This is where I found this set in particular.
Him and Ho-oh kind of... clash. I have a cool replacement though, don't worry.
A scarf user really does help in Ubers.
Set name: I <3 STAB
EVs: 4 HP / 252 Atk / 252 Spd
Volt Switch seems gimmicky to some, but I assure you it's amazing. It's mainly to revenge kill low HP opponent then switch into something safe. Bolt Strike is STAB that pounds like mad. It hurts. Outrage is in the same spot. Dragon Claw is a more safe approach with the whole " not being confused after 2 turns " thing.
With my current suggestions, you would have 3 dragon weaknesses, and 3 neutral hits. A Jolly C-scarf Zekrom could probably KO your entire team. Which is why I say that Ferrothorn still works in Ubers.
Ability: Iron Barbs
EVs: 252 HP / 252 Defense / 4 Sp Def
This guy adds hazareds into the mix, can cripple fast threats with Thunder Wave, can use Leech Seed to help Kyogre be more bulky, Ho-oh stay alive through recoil, Arceus set up Swords Dance safer, and Rayquaza and Zekrom recover from Outrage easier. Power Whip can attack if taunted, and mainly take out things like Kyogre.
Besides that, nice team Dr. Flame! Hope these suggestions help you. If you have any problems, just comment and I'll see what I can do. ( Just be aware that I only have access to a computer for the next 2 days, most likely. )