Another set of avatars has recently been added to the official Pokemon community forums, this time featuring the Johto mons. Note that all legendaries are still not included, so I was mistaken in saying the first 149 mons since the legendary birds aren't here yet. The original Unite avatars still have not returned, so I will personally be keeping the homeless Charizard avatar as a remnant of that time.
The background colour for each avatar also mostly seem to be based on the Pokemon's primary type, but some birds like Pidgey and Spearow seem to get a sky blue Flying colour while Doduo and Farfetch'd are Normal grey.
Since I didn't really give a detailed showing of them before and most people probably won't look to see all the options, I decided to go through these and share my top and bottom picks of each region roughly based on how I feel about them as images out of context, using/seeing them as avatars, and their composition, putting aside from my feelings on the mons themselves.
Of all the Unowns you just get Unown-F which I like.
Wobbuffet has one of the more dynamic poses but also Noctowl of all mons gets an action pose. Also Hitmontop is properly upside down.
I think these side-facing angles fill up the circular space best compared to some other mons facing more straight ahead which I don't like as much.
Both bear avatars have a unique vibe to them.
And here are my preferred picks for Kanto, mostly due to their simplicity:
Honourable mention goes to Voltorb/Electrode for not quite taking up the whole avatar but still displaying visible emotion and contrasting. Also Poliwag fits really well with the circular frame with how it's walking.
While I was getting these images anyway, here are my options near the bottom of the list for Kanto.
And here are my bottom options for Johto:
