Ay I know this question has been answered, but I’ll give it a shot.
Starting things off, Tyranitarite takes up you item slot. While this isn’t necessarily that bad, Tyranitar usually benefits from things like a Choice Band/Weakness Policy to boost its attack. Mega Evolving does boost its base Attack by 30 though. The problem with this is that getting the 2x boost from a Weakness Policy works better.
I feel like the boosts to its defenses are nice when it Mega Evolves, but hitting harder could be the difference between winning and losing a battle. With Jolly and max Attack EVs, Mega Tyranitar hits a whopping 427 Attack without boosts. With Jolly and it’s Weakness Policy activated, again, with maxed out Attack, regular Tyranitar hits 672 Attack. So obviously, a Tyranitar with +2 Attack has a higher Attack stat than a Mega Tyranitar.
Of course, Mega Tyranitar can Dragon Dance to boost its Attack, but so can regular Tyranitar. That means, in one turn, a Tyranitar can get to +3 Attack, while a Mega Tyranitar can only get to +1.
I will say though, Mega Tyranitar’s defenses are great, and it gets a +10 boost to its base speed, so it has the advantage in hitting before a regular Tyranitar would. So really, it’s your choice which one you would go with. I would stick with a Weakness Policy + Dragon Dance Tyranitar, but it’s up to you. Here’s sets for both of them:
Tyranitar-Mega @ Tyranitarite
Ability: Sand Stream
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Crunch
- Stealth Rock
- Stone Edge
- Dragon Dance
Tyranitar @ Weakness Policy
Ability: Sand Stream
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Crunch
- Earthquake
- Dragon Dance
- Stone Edge
So, I would use Tyranitar for setting up sand, but I would not mega evolve it. Even though it’s Mega is great, I feel like it benefits more from not having its item slot taken up by a Mega Stone. Really, they’re pretty even. So yeah, I think Tyranitar is a great sand setter, and I do recommend it. It’s Mega is good too, just I think it’s base form is better.
Hope this helps! :)