PS4 has all the big multiplats and generally has many more games. Switch depends more of its Nintendo games and has thus less big games.
Thus, Nintendo's exclusives have a bigger impact on Nintendo's hardware sales. Pokemon+Smash is an extremely formidable opponent for Sony.
3DS did have a Smash+Pokemon combo back in 2014 but the circumstances were a bit different.
1. 3DS was in its 4th holiday and had a price cut, 2 revisions and many bundles by this time, Switch will only be in its 2nd holiday, has yet to receive a price cut, revisions or value bundles.
2. Pokemon was a remake and the 2nd pair of Pokemon games on the system. If Pokemon releases this holiday on Switch it will be a new generation and the series debut on the system.
3. Smash Bros had to share a release with the Wii U version which released about 1.5 months later. Smash Bros on Switch doesnt have to worry about sharing sales with another system.
3DS did well in Q4 2014 (~1.5m) with Smash+Pokemon but not amazing but those points i outlined above means a Smash+Pokemon combo along with a Black Friday discount or bundle gives Switch significantly higher potential than 3DS had in 2014.