Critics won't be nearly as turned off by Let's Go as some fans are. It's a pretty, more accessible version of gen. 1. I'd be very surprised if it gets lower than 75 and would actually predict low 80s.
Smash might start to suffer from franchise fatigue. I saw some outlets lower the score of Smash Wii U in 2014 because they had grown tired of the formula,and I suspect that trend might continue here even if has more content and more refined gameplay than previous versions. So low 90s to high 80s; I think a lot is riding on the spirits system really taking off since they're dropping trophies, which is a huge mistake in my opinion.
While it’s unfortunate that trophies won’t return, I can understand why. They built over 900+ 3D/2D models as trophies, how can you do all that work + possibly 100-200 more within less than 3 years of development while having to deal with World of Light, getting every veteran back, getting new characters, new and old stages, over 900 music tracks, etc. all in HD.
plus Spirits appear to be allowing these spirits of many characters of many franchises to be useful, especially in events in World of Light.