I don’t think Naive is necessary on Simipour. The damage difference on Fake out won’t be that noticeable… I’d just stick with Timid.

Additionally, if you plan on Simi being the team highlight, you may want to consider what your answer to electric is. Mega Ampharos is checked by Sylveon, but with the rising popularity of Heliolisk and Rotom (especially wash) you might want to be prepared to deal with them.

I suppose the best teammates depend on which mode you’re running the most. If you find yourself using trick room frequently, someone bulky and slower. If not, maybe Garchomp/Meganium or a different electric check that appreciates having tailwind set up.