Yeah mixed nite with multiscale will lose out on superpower which is a mehI mosly play ou but keldeo is great, also mixnite never works for me because life orb is the best item and it breaks multi scale and i end up getting ohkoed a lot, although i will try out mixmence.
Also i find cb terrakion to destroy skarmbliss and most defensive cores but it requires a lot of prediction for the correct move
Also cb terra is nice but out of the things you mentioned...it gets wrecked by gliscor...and jellicent can be a problem if you dont run eq
For mixed mence I always feel like it's not bulky enough though but yeah