Shiny Venonat Guide Pokémon Go will arm you with knowledge about the special Venonat encounter.
Shiny Venonat will be featured during the Throwback Challenge 2020 Kanto event. You'll be able to find more Pokémon originally found in Kanto, and the event features Shiny Venonat in the wild.
Shiny Venonat Guide Pokémon Go: Rarity
Normally, Shiny Pokémon are encountered roughly once out 450 times for any particular Pokémon in the wild. During events, that rate may be as low as once in 130 encounters.
If the Venonat has blue eyes instead of red, it's Shiny. It will also have a sparkle over it when the encounter begins.
Shiny Venonat Guide Pokémon Go: How to Find and Catch
To find Shiny Venonat, you'll have to look for normal Venonat on the map. You won't know it's Shiny until you encounter it. Once you do, it's as simple as catching any other Pokémon. Venonat is easy to catch, so you won't have problems with the Shiny.
Shiny Venonat Guide Pokémon Go: Counters
Venonat evolves into Venomoth, an interesting Bug/Poison type that is unfortunately hindered by its low CP. It is good against Fighting type Pokémon, as its typing resists those moves and can learn Psychic attacks like Confusion to deal with them. Venomoth's typing and move set is somewhat unique, allowing it to deal with Fighting, Poison and Grass types extremely well.
Your best choice against Venomoth is to go with straight Fire or Rock types. Blaziken and Infernape can be vulnerable to Venomoth's Psychic moves, so be careful with what dual types you throw at it.