How can I view which Pokémon I've buddied over time?
Solution 1:
The version 0.49.1 Andorid/1.19.1 iOS released a feature which allows you to view each Pokémon you have buddied and how many kilometers you have accumulated with that Pokémon.
The total kilometers a buddy has walked has been added to the information screen of each Pokémon that has ever been your buddy.