I'd like to point out that, while your team has some strong mons, you are really weak to some of the metagame's biggest threats. Let me name a few:
Deoxys-Attack: this thing always gets a kill, or dents half of your team. Since you don't seem to have a dedicated lead, it can easily spam LO boosted moves, such as Superpower, Psycho Boost, Knock Off, Thunder Punch, etc., while it can also use Extreme Speed to get a last ditch effort to get some chip damage on you. Giratina would seem like your best bet, but Deo-A isnt afraid of your nonexistent hazards, so it can come in later. However, while I'm making Deo-A seems like a god, you have enough checks to it to come out a victor against it. It'd certainly be a class A threat, not enough to be a Class S threat to your team, thanks to your 2 priority users.
LO Xerneas: This thing absolutely destroys your team, bar Mewtwo. Since it runs Close Combat, Rock Slide, and Moonblast, it gets a SE hit on all your mons bar Kyogre and Mew2Y. However, Kyogre cant do jack crap to it, thanks to Xerneas' amazing bulk, it will force you to stay locked into surf, as I'm sure moonblast would do a good 60% to Kyogre. Rock Slide OHKO's Ho-Oh, and Giratina is OHKO'd after rocks (which is damage he will be forced to take, due to being your Defog mon), and downright destroys Yveltal if it happens to run Max Speed. Arceus is hella dented by CC; enough to the point where said Deoxys-A can come back in and Extreme Speed you for the KO.
Mega Blaziken: this thing just plows through your team, OHKO'ing everything at +2. Thankfully, you have coverage on all your mons to threaten it, but if it comes on a Choice locked Ice Beam from Kyogre, say your GG's. It will surely OHKO all but Ho-Oh and Giratina with Low Kick + Flare Blitz, and it gets to Knock Off kill on Ho-Oh (after rocks) and Giratina (after rocks). As stated, you can pressure it offensively, but be wary to not make a mistake. It doesn't even need +2 to sweep, granted you're weakened enough.
