Niantic has announced that to celebrate spring in the northern hemisphere, an event will take place from Sunday, April 4th, 2021, at 10:00 a.m. to Thursday, April 8th, 2021, at 8:00 p.m. local time.

Celebrate spring in Pokémon GO with the debut of Mega Lopunny!

Trainers, Spring has sprung in the northern hemisphere, and we’re celebrating with a spring-themed event! Look out for Chansey, Happiny, and some other familiar Pokémon wearing flower crowns. Plus, Mega Lopunny will be making its Pokémon GO debut in Mega Raids!

Date + Time
Sunday, April 4, 2021, at 10:00 a.m. to Thursday, April 8, 2021, at 8:00 p.m. local time

Features

• The following Pokémon will be appearing more often in the wild: Pikachu wearing a flower crown, Exeggcute, Marill, Plusle, Minun, Buneary, Bunnelby, and more. If you’re lucky, you might encounter a Shiny Bunnelby!
• Chansey wearing flower crowns will be appearing in the wild, and Happiny wearing flower crowns will be hatching from Eggs! If you evolve a Chansey wearing a flower crown into Blissey, that Blissey be wearing a flower crown, too. If you’re lucky, you might encounter a Shiny Chansey or a Shiny Happiny!
• Shadow Exeggcute will be appearing more often in Team GO Rocket battles!
• The following Pokémon will be hatching more often from 2 km Eggs: Exeggcute, Eevee wearing a flower crown, Pichu wearing a flower crown, Togepi, Azurill, Buneary, Happiny wearing a flower crown, Munchlax, Rufflet, and Bunnelby.
• Mega Lopunny will make its Pokémon GO debut in Mega Raids! Other spring-themed Pokémon will be appearing in raids as well. There will also be Mega Lopunny–inspired avatar items available in the shop!
• Event-exclusive spring-themed Gift stickers will be available from PokéStops and Gifts during the event, so be sure to get them while they’re available!
• Complete event-exclusive Field Research tasks to encounter Azumarill, Rufflet, and more!
• Complete the spring-themed Collection Challenge during the event by collecting featured Pokémon to receive a Lucky Egg, Mega Lopunny Energy, and XP. Head on over to the Today View to track your progress!

Bonuses

• 2× Hatch Candy
• Lucky Eggs will last for one hour
• 1/2 Egg Hatch Distance when you place an Egg in an Incubator during the event

Please be aware of your surroundings and follow guidelines from local health authorities when playing Pokémon GO. Upcoming events are subject to change.

Source: https://pokemongolive.com/post/springevent2021