When I loaded up Pokémon Go today, I noticed something that was out of the ordinary. At one of the pokéstops in the nearby list, there was the silhouette of a Turtwig, as if uncaught, despite having caught many Turtwig prior.
As shown in the screenshots below, the Turtwig's silhouette appeared even though my Pokédex shows I have caught 107 of them.
Two things came to mind:
This occurred right after the announcement of new shadow Pokémon, which Turtwig was in the list. However, the pokéstop was not being invaded by Team Rocket.
It was potentially a gender I had not caught, which acts this way on the evolution button if you do not own the gender of that evolution. However, I have both male and female Turtwigs.
So my question is: Why would a Pokémon's silhouette appear even though I've caught it before? No other Pokémon behaved this way, so it seems like something was happening with this Turtwig in particular.