Ready for starmie solo

Against Psychic-Starmie, I would also consider Exeggutor. However, I suppose you will be fine with your team, as Starmie is rather fragile. The Tyranitars could be destroyed by Hydro Pump though.

You Should be fine. I just did it with this setup. Starmie went Down just before jolteon did. I Dodged a few power gems.

Exeggutors aren't that good since Confusion/Extrasensory is NVE, maybe Sceptile is better here, though, Fury Cutter is SE.

Raikous are level 30 and 25ish, Mewtwo is level 35 and Tyranitars level 30 ish? Should be fine but undodged HP will wreck your TTars as said so consider swapping in your best grass types if that gives you trouble.

It's new, try it anyways. But you should be good. BS/SoB exeggutors should be helpful here too. Solar beam does massive damage.