Looks like u already started working toward weakness-balancing for Ground/Fighting/Water/etc move toward your Rock team by including Aero, Lunatone, Cradily (shame Cradily doesn't have Storm Drain yet in this game thou).
I'd suggest starting off deciding which tier (OU/UU/NU) you want to play this mono team in Pokemmo first, then you will be able to see clearly what are the prominent threats to your team. That being said, if u have Tyranitar, then its OU. Taking it off, then its NU. So take that into consideration.
In case you just want to play this as a fun style versus friends, then feel free to ask more specific questions.
Some random suggestions of good Rock mons to you could be Omastar and Crustle with Shell Smash setup, Rock Polish Rhyperior, or even Armaldo for hazard setup and spinner. Decide a play style and the roles your team lacks is important.