This team is weak to Extreme Killer Arceus, Blaziken, Calm Mind Kyogre, and strong Dragon Pokemon such as Rayquaza, Kyurem-B, and Kyurem-W. Once they get the chance to setup, you have nothing to stop them bar Arceus's priority, which no experienced player will leave his team that awfully weak to opposing Extreme Killers.

Blaziken, however, can literally can sweep your team once that Groudon is weakened (not a problem at all), Arceus is gone/burned, and with its extremely wide coverage and ability to easily setup with Protect. Having no Steel-type really hurts you badly, as strong Pokemon, such as Rayquaza, can simply come in, setup, and wreck you. Mixed Dancer Rayquaza is also capable of beating Groudon with Draco Meteor. Calm Mind Kyogre can also be threatening as after a few Calm Minds even Palkia won't stand up against it; however, due to the natural offensive type of this team, repeated hits might be able to take it down, but I wouldn't rely on that solely.

Phys. Def Gira-O > Reshiram
Steel Arceus > Extreme Killer
Latias > Kyurem-W
Genesect > Palkia