Regionals

I think Zangoose and Seviper was the only instance IIRC. Most likely won’t happen again

They have been flipped for certain events, though. That may happen

The only ones that have switched so far are Zangoose and Seviper. Additionally, Plusle and Minun became available everywhere after being regional since their release. There is no established schedule for this so nobody knows when the next one might come.

Solrock and Lunatone were speculated to rotate on vernal equinox but it seems they didn't.