Update on my alt phone: It fixed itself for around a week, then went back to not working again. There are three problems that seem to be interrelated, since they pop up together: (1) Google Fit does not track distance; (2) AR+ in Pokemon GO does not load; and (3) the screen does not auto-adjust brightness based on the amount of ambient light. Who knows. But while the phone was working, I got up to 63 Sandile candy. Just over halfway there.
Meanwhile, on my main, I got to best buddies with my two Gen 1 megas: Masaru the shiny Charizard, and my as-yet-unnamed shiny Beedrill.