Spinda has been around in Pokémon Go as a field research reward for something over a year. Since then, Spinda forms change at more or less fixed intervals (typically monthly). Spinda remains only accessible by field research.
In my experience, the tasks giving Spinda have increased significantly in rarity since around March; I only found three in the past six months. I currently have one saved that I do not want to ‘waste’ on a Spinda form I already have (I know they are being rereleased as shinies but I consider the odds of encountering a shiny Spinda too low to ‘waste’ my Spinda catching chance on one).
Is there a place which lists the currently available Spinda form plus the time until/date when the next shuffle is expected? Bonus points for a site that includes a record of past available Spindas.