The players have voted, and Rhyhorn will have its own Community Day on Feb. 22.

After a player vote, the star of the next Pokémon Go Community Day has been chosen: Rhyhorn.
The Community Day will be on Feb. 22. For players in the northern hemisphere, itll take place from 11 a.m. until 2 p.m. in your local time zone. For players in the southern hemisphere, itll take place from 3 p.m. until 6 p.m. in your local time zone.
The Community Day will feature Rhyhorn spawning at an increased rate, with a high chance for it to appear Shiny. Catch Stardust will also be tripled throughout the duration of the event.
When evolved during the event period and up to two hours later, Rhyperior will learn Rock Wrecker, which makes it a fairly solid raiding Pokémon, but it still falls behind Rampardos in DPS. Rhyperior does need a Sinnoh Stone in order to evolve, and there is no word on any extra Sinnoh Stones being given out during the event.
Rhyhorn was picked by players when pit against Machop, Dratini, and Vulpix. Vulpix and Rhyhorn were both set to have their Shiny forms added to the game for the first time, with Dratini and Machops Shiny forms added long ago.