You don't need max speed on Starmie, winning ties in the mirror match won't do you much good, especially when you've got Rotom-W to counter it. I'd drop the investment to 216 to outrun Gengar and then you can throw a few more EVs in Defense to help out a bit against Terrakion.
Not once in all my matches using that Landorus set have I needed Timid's speed, whereas Modest's extra power is quite useful, so I'd try that out.
I think SpDef Hippowdon would work in place of Tyranitar. Not only is Tyranitar a pretty awful mon in this metagame that doesn't do much besides set up sand and kill Keldeo counters, but Hippo also gives you a Rock resist, and in general a solid Terrakion counter. It's also a much sturdier weather inducer that stupid Sun teams can't just trap with Dugtrio, and it can also check the Therians with Ice Fang in the last slot. You've got Landorus' counters checked very nicely between Heatran and broken ass Genesect, so Ttar's trapping abilities won't be missed too much.
With SR on Hippo, you can try some different options on Heatran, like Flame Charge, Will-o-Wisp, etc. I also think max speed on Tran is a waste, so I'd drop it to a benchmark and then add some extra bulk.
Cool team, hope this helped