You might not last in that Tournament because they have no Uber ban. Meaning some kid with his Team of 6 Pokemon out of these Regirock, Regice, Registeel, Latios, Latias, Kyogre, Groudon, Rayquaza could easily defeat anyone. The one thing little kids lack is using EVs. My thoughts on winning that Tournament are you need to use some good Ubers with some good IVs, EVs, and Movesets. Your Team is good but I just don't think it'll last against the Ubers and Legends.