This looks like a really solid team, and with some changes it might improve in performance.
First of all, I do have to second using LO Starmie b/c MixApe wrecks and you're lacking speed, with the exception of Scarftar of course. If this change goes through I want to suggest changing Scarftar to DDtar. The set should look like the following: Tyranitar@ Babiri Berry | Jolly Nature | 4 HP / 252 Atk / 252 Spe | Dragon Dance / Crunch / Stone Edge / Fire Punch. I could suggest another more interesting version, but I feel this will replace in a sense Agilitygross as a solid sweeper.
Next, I want to suggest giving Rotom a Scarf, looking like Rotom@ Choice Scarf | Timid Nature | 4 HP / 252 SpA / 252 Spe | Thunderbolt / Shadow Ball / Will-O-Wisp / Trick. This change will give you an Agilitygross, DDGyara, and SDLuke check, which your team needs. I suggest Will-O-Wisp in there to catch countless pokemon off guard like all the grounds that might want to switch in for a Tbolt. This cripples potential counter to DDtar and Jirachi. If it doesn't pull its weight then just switch back to Overheat.
Now for the final and most interesting change, switching Jirachi to a Superachi variant. The set is Jirachi@ Leftovers | Timid Nature | 4 HP / 252 SpA / 252 Spe | Calm Mind / Psychic / Grass Knot / Hidden Power Ground OR Thunderbolt. The niche of this set is to catch it usual counters off guard and retaliate with a sweep. Not only does it also provide a second check to SDluke, but gets rid of DDtar counters for an easy sweep. The drawbacks are the lack of Wish and the key choosing of the last moveslot.
Might seem like a drastic change, which I hate including in my rates, but I feel it gives you that offensive push you are looking for. The team was too slow imo with no entry hazards to support it. Remember, these are just suggestions and leaving what you're comfortable with is probably the best decision.
Hope this helps you out, and good luck with the team!
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