The totals looked pretty similar for every month except November. Looks like Pokemon Let's Go is what really pushed the Switch over.
Although another perspective would be that Nintendo had a very weak first party line-up all year for Switch, and once they got a solid title then they actually were able to pull ahead of 3DS+ Wii U. If this is true then they should continue to pull further ahead of 3DS + Wii U if they continue to get solid titles in 2019.
curl-6 bet me that PS5 + X|S sales would reach 56m before year end 2023 and he was right.
My Bet With curl-6
My Threads:
Master Thread, Game of the Year/Decade
Switch Will Be #1 All Time
Zelda Will Outsell Mario (Achieved)
How Much Will MH Rise sell?
My Bet With Metallox