Well, after a bit of analysing the dragons den, I came to the following team:
Gigalith,Tyranitar, Magcargo, Tyrantrum, Aerodactyl and one free slot. The Gigalith is obvious since it is seen. The Tyranitar is a very powerfull sandstorm setter and it can learn dragon dance. The Tyrantrum is quite obvious due to the dragons den. Magcargo is a bit strange since its stats and typing leaves a bit to be desired but it gets a lot of nice field boosts due to magma armor and it's boosted fire stab. The Aerodactyl will be his counter to ground and fighting. While Solrock and Lunatone are good anti-ground and fighting types as well, their lower base stats plus the fact that Aerodactyl's weakness to ice is covered by the field, makes them less likely. Personally I think the Aerodactyl will be the mega over Tyranitar symply because tyranitar is more of a lead and has a bit more weaknesses, one even a 4 times weakness.