You can predict like with any other raidboss...wait for Kyogres attack when he's in the middle...immediately start throwing your curveball and the ball will land in the circle during the time frame where Kyogre is not able to move after his attack...it's harder because of the smaller cirvle near the ground but in the end it's the same as usual.
Kyogre nightmare
I managed to get a terrible iv kyogre with the penultimate ball of my 9th raid. Must have landed nearly 70 throws on it in total today. So difficult to land anything decent and it double/triple attacks and moves sideways so you cant predict like with Groudon. Not really a question, need to vent some anger!
Answers
I did that when he did the 1st attack.. But when the ball nearly hits him, he did a 2nd attack right away.. This happens multiple times where I lost around 4-5 balls.. If I threw slightly earlier, it got blocked coz the attack animation hasn't ended.. Kyogre is definitely harder than Groudon... And till now, I can only land Great Throw 30% of the time and 0% Excellent throw.. For Grouon, it is around 80% Excellent and 20% Great.. Lol
The move sideways doesn't happen during an attack, so there's no problem with prediction as with groudon.
However, since it can also attack having already position (and you will unlikely want to challenge the throw by then), you will waste a lot of time if you try to be patient. Sadly, that's the only way you can do to maximise catch chance.
A zero IV Kyogre is so much better than many other great attackers. I caught my first and only one (only had an opportunity for one raid so far) with a straight great throw. When I tried curve (and I can throw great curve balls now.... rarely excellents, though) I usually missed him.
Good luck, hope your next one has great IVs!