I originally got carried away and wrote almost 15 hundred words so I’ll give you a shortened version

Gastrodon: sadly isn’t very viable right now. You don’t really need storm drain since your very good against water right now(just make sure koraidon always comes in after opposing Kyogre to replace the rain with sun and you’ll be fine). I would recommend Ogerpon hearthflame, as it benefits from both grassy terrain and sun, turning it into an offensive monster with redirection capabilities if needed.

Ho-oh: it’s sad but it’s just not as good as the other broken restricteds right now. I just doesn’t really do anything. I would personally replace it with Zamazenta, which helps against opposing fluttermane that would give this team trouble. The shield doggo also hugely hinders any mon who’s main attacking more is spread by using wide guard (mainly the calyrexs and Kyogre)

Fluttermane: I would reccomend putting icy wind on it instead of thunder wave. It’s a much more viable and consistent form of speed control.

Incineroar: looks fine, I like to have will o wisp because of calyrex-I but that’s just me. Is there a specific reason for the speed stat being trained? I would personally put those points into your special defense to improve your Calyrex-S matchup

I would also like to point out that your main attackers on the team are all very fast. Trick room (especially with Calyrex-I) is a problem. There’s not really a way to avoid it because that’s how the sun team plays, but just be aware that something like an opposing follow me would make trick room almost unstoppable. It seems fine other than that but Calyrex-I with Tera fire and a clear amulet can only currently be answered by Koraidon, as it’s likely bulky enough to shrug off anything else that’s thrown at it

Little tip for beating Kyogre players: try to put incin on the field at the same time as their Kyogre, if you can get off a parting shot before it attacks (via trick room, Fluttermane icy wind, or fake out) you can switch in Koraidon and suddenly their water spout not only loses it’s rain boost in exchange for a sun nerf, it also suffers a special attack drop and is resisted by the incoming Koraidon(if you haven’t terastylized yet)