Using a Raquaza is a good idea. I opened with a Fearow that had Flash, Double Team, Taunt and Sand Attack. I used Flash and Sand Attack the most, to completely minimise it's accuracy. Then, after Fearow got KO'ed, i switched to Sceptile. I know it seems strange, but every time I've caught Kyogre, Sceptile has always helped me. :)
Sheer cold won't even be able to hit because of Flash and Sand Attack, Hydro Pump isn't very effective (it will probably miss, too).
I gave my Sceptile this moveset specifically to catch Kyogre :
=>Giga Drain (to take more hits)
=>Leaf Blade (it has good damage and PP)
Give it either the Big Root or the Focus Sash. I tried with both, they're equally effective.
Use Leaf Blade to weaken it, and keep replenishing hits with Giga Drain. When it rests, use one or two Leaf Blades to get it low enough, and keep false swiping it. Now you have two options :
-> Switch to Raquaza (to prevent double edge from killing itself) and use a mixture of Ultra Balls and Timer Balls (in EVERY game I've played so far, I've always caught all of the three in Timer balls) to catch it.
-> Stay with Sceptile till it dies, revive Fearow and taunt Kyogre. Then continue with sand attack / flash. Use Timers and Ultras all the way through. :)
I hope this helped. ^^