Starmie will be smashed by Psytrike easy. You miss out the OHKO for max HP Ghost Arceus, in exchange for outrunning base 102+ threats, which is still fairly important. The problem is Kabutops outruns quite a lot of threats in rain and gets a lot more chances to spam attacks. Hitting Groudon hard is a good thing though, and I guess you beat Rayquaza one-on-one which is good. Other than powerful Hydro Pumps on the switch, getting Starmie in is almost impossible. Kabutops can use Swords Dance on the predicted switch and OHKO Ghost Arceus. Giratina-O still takes loads of damage close to OHKO after rocks. Starmie can OHKO Ghost Arceus on the switch, but Kabutops outruns Ghost Arceus which is huge. The Rock-typing gives Kabutops a lot more use.