The first thing I would suggest is running a bulkier T-tar. You already have a great scarfer against Psychics in Geno, and the momentum it generates for your team is probably more important then the guaranteed kill. This allows Tar to come in a little more often against strong special attacks. The set i'm recommending is this.
Tyranitar (M) @ Choice Band/Leftovers
Trait: Sand Stream
EVs: 136 HP / 252 Atk / 120 SDef
Adamant Nature (+Atk, -SAtk)
- Stone Edge
For you I would recommend leftovers. This is a powerful physical attacker who can force switches, allowing you to pave the way for your main physical sweepers. Obviously it has problems with groudon, but at least it lures it in to get a little damage on it since your team obviously needs it gone. Since Groudon is going to be switching into your Tar so much, one option is to go mixed. Ice beam or Fire blast will both do good damage and will at least dissuade it from switching in in the future. Pivoting to Shandy is prob still your best option though, and splitting evs could hurt. If you do decide to run leftys you could probably fit sr in the set somewhere.
I agree with the Grass arceus suggestions, but scarf ogre is still a problem as you know from playing me! Specs palkia can't really be fixed either except by completely changing your team structure.
All in all good sandteam in Ubers. Good Luck!
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