What determines whether I can see a Pokémon's size records in the Pokedex?

Question

Pokémon GO recently added a feature that lets you see whether a Pokémon is the tallest, shortest, heaviest, or lightest that you've caught of that particular species. The records are also available in that species' Pokedex entry, but I can only see them for certain Pokémon, and there doesn't seem to be any rhyme or reason to which Pokémon have it and which don't:

• Some Pokémon that I've caught since the update don't have data, while some that I haven't caught/evolved in months do
• Some Pokémon that I've caught/evolved dozens of times don't have data, while some that I've only caught/evolved three or four times do
• Most Pokémon lines only have data for their evolved forms, while others only have data for their unevolved forms

It must have this data for every Pokémon I've caught, otherwise how would it know whether I've beaten a record? But why is that data only visible for some Pokémon and not others?

Answer 1

To see the size records for a Pokémon in the Pokédex you need to have had at least three different copies of that Pokémon in your storage since you installed the updated app version. These can be either 3 of that Pokémon you had sitting in storage as the application went live, or 3 new ones that you caught since then, or a mix of the two. They don't all need to be in storage at the same time, so you could catch one Pidgey, transfer it, repeat two more times, and the size record entry will appear for Pidgey in your Pokédex.

This is mentioned in the announcement blog post, although they don't explicitly state that it's not retroactive:

Once you catch at least three of any one Pokémon, your Pokédex will begin to showcase your records for the largest, smallest, heaviest, and lightest specimens that you have caught.

It is worth noting that evolutions do count as a "catch" as far as this system is concerned.