By including Giratina, your officially bumped into the ubers tier. Which means your swimming with the big sharks, more specifically Garchomp, Mewtwo, Palkia, Kyogre, Groudon, etc. That basically means your going to have a hard time if that's what you intend to bring to the table. Nothings really stopping a Kyogre from spamming Water Spout/Hydro Pump aside from Giratina or Empoleon, the latter who you can't really use until you know what item it has (Choice Scarf/Specs) as it gets dented (quite hard) with Thunder. Same applies to Mewtwo, who will just have a lovely day pretty much smacking almost everything on your team supereffective with just Ice Beam and Aura Sphere.
I would personally just say toss out the Giratina, but then again your probably just playing for fun, in which case have fun.