I, like most sensible people, wouldn't run Bright Power AdamantChomp as my best check to Latios, if that's the case, you are going to get stabbed in the back at some point. Tyranitar already functions as a great Latios check, so I'm going to be boring and say, "yes, you need a Yache JollyChomp".
The Tyranitar should really be 4 HP/252 Atk/252 Spe with Adamant and a Focus Sash, since this isn't a dedicated Sandstorm team, and you're simply using it either for the power TTar dishes out or the ability to throw other weather teams off balance. Either way, you may find yourself appreciating the extra speed, especially in Tailwind.
Latios, I think, should have another STAB attack somewhere, in the form of either Psychic or Dragon Pulse. Either gives him a reliable way of taking down an opponent which you can most safely take out with Latios and don't want to spend 2 stages of special attack to do it.
Hope I helped, good luck!
...You were expecting a signature?