Niantic has announced the full details of the March 2021 Pokémon GO events.

A new Season is coming—and so are March’s Pokémon GO events!

Trainers, We hope you’re prepared for a month of exciting Pokémon encounters and bonuses!

Incoming: New Team GO Rocket Special Research!
It appears that after a few months of rest, Giovanni and his Grunts are up to no good once again! What’s worse, they’ve obtained more Shadow Pokémon—including Shadow Legendary Pokémon! Early investigations into Giovanni’s movements suggest he’ll be using these Shadow Legendary Pokémon at different times.

• March 2021: Shadow Articuno
• April 2021: Shadow Zapdos
• May 2021: Shadow Moltres

Starting on Sunday, February 28, 2021, at 12:00 a.m. local time, play through this Season’s new Team GO Rocket Special Research to earn a Super Rocket Radar and take down Giovanni! There will be other opportunities to earn Super Rocket Radars at the beginning of each month this Season, so stay tuned for more information!

March Research Breakthrough encounter
From Monday, March 1, 2021, at 1:00 p.m. PST (GMT −8) to Thursday, April 1, 2021, at 1:00 p.m. PDT (GMT −7), you’ll encounter Gible in Research Breakthrough encounters.

Featured Pokémon in five-star raids and Mega Raids
The following Legendary Pokémon will be appearing in five-star raids throughout March.

• Incarnate Forme Landorus will be appearing in five-star raids from Monday, March 1, 2021, at 8:00 a.m. to Saturday, March 6, 2021, at 8:00 a.m. local time. If you’re lucky, you might encounter a Shiny one!
• Incarnate Forme Tornadus will be appearing in five-star raids from Saturday, March 6, 2021, at 8:00 a.m. to Thursday, March 11, 2021, at 8:00 a.m. local time. If you’re lucky, you might encounter a Shiny one!
• Incarnate Forme Thundurus will be appearing in five-star raids from Thursday, March 11, 2021, at 8:00 a.m. to Tuesday, March 16, 2021, at 10:00 a.m. local time. If you’re lucky, you might encounter a Shiny one!
• Therian Forme Thundurus will be appearing in five-star raids from Tuesday, March 16, 2021, at 10:00 a.m. to Tuesday, March 30, 2021, at 10:00 a.m. local time.
• Therian Forme Tornadus will be appearing in five-star raids starting Tuesday, March 30, 2021, at 10:00 a.m. local time.

In addition, the following Mega-Evolved Pokémon will be appearing in Mega Raids.

• Mega Blastoise, Mega Pidgeot, and Mega Ampharos will be featured in Mega Raids from Monday, March 1, 2021, at 8:00 a.m. to Tuesday, March 16, 2021, at 10:00 a.m. local time.
• Mega Houndoom, Mega Abomasnow, and a surprise Mega-Evolved Pokémon will be appearing in Mega Raids starting Tuesday, March 16, 2021, at 10:00 a.m. local time.

Every Wednesday in March will feature a Raid Hour event from at 6:00 p.m. to 7:00 p.m. local time. Raid Hours will feature the Pokémon appearing in five-star raids that week. A bonus Raid Hour will be taking place on Monday, March 15, 2021, from 6:00 p.m. to 7:00 p.m. local time. As a reminder, when the Season of Legends begins on March 1, 2021, you can gain extra XP for completing five-star raids! Stay tuned for the April events blog for more details on the next Pokémon to be featured in raids.

Pokémon Spotlight Hours
In the month of March, Pokémon Spotlight Hour will take place every Tuesday at 6:00 p.m. local time, and each of these will spotlight a different Pokémon and special bonus!

• Tuesday, March 2, 2021: Krabby will be in the spotlight, and you’ll earn twice the Candy for transferring Pokémon.
• Tuesday, March 9, 2021: Drowzee will be in the spotlight, and you’ll earn twice the XP for evolving Pokémon.
• Tuesday, March 16, 2021: Voltorb will be in the spotlight, and you’ll earn twice the Stardust for catching Pokémon.
• Tuesday, March 23, 2021: Surskit will be in the spotlight, and you’ll earn twice the XP for catching Pokémon.
• Tuesday, March 30, 2021: Slugma will be in the spotlight, and you’ll earn twice the Candy for catching Pokémon.

March Bonus Hours
We will be testing Bonus Hours throughout the month of March. These tests will take place on the listed Thursdays at 6:00 p.m. local time, and each one will feature a unique bonus!

• Thursday, March 4, 2021: GO Rocket Hour — Team GO Rocket Balloons will be appearing more frequently. Be on the lookout, Trainers!
• Thursday, March 11, 2021: Mega Bonus Hour: Candy — You’ll earn more Candy when you catch Pokémon that share a type with your active Mega-Evolved Pokémon.
• Thursday, March 18, 2021: Mega Raid Hour — Mega Raids will be happening more frequently.

March Community Day Featuring Fletchling Join us on Saturday, March 6, 2021, from 11:00 a.m. to 5:00 p.m. local time for a fiery Community Day featuring Fletchling. Evolve Fletchinder (the evolved form of Fletchling) during the event or up to two hours afterward to get a Talonflame that knows the attack Incinerate.

Upcoming new events
Look out for more details coming soon for these events.

• Searching for Legends—From Tuesday, March 9, 2021, to Sunday, March 14, 2021, join us as we begin our journey to search for Legendary Pokémon! And what better way to sniff out these Legendary Pokémon than with the Compass Pokémon, Nosepass? Who knows—if you’re lucky, you may even encounter a Shiny Nosepass!
• Incense Day: Psychic-Type and Steel-Type —We are hearing reports that on Sunday, March 14, 2021, more Psychic-type and Steel-type Pokémon will be attracted to Incense, including Beldum!
• **Charge Up!**—From Tuesday, March 16, 2021, to Monday, March 22, 2021, get amped for an event where Electric-type Pokémon will make their Pokémon GO debut!
• Weather Week—From Wednesday, March 24, 2021, to Monday, March 29, 2021, experience a whirlwind of weather-themed Pokémon appearing in the wild and new avatar items, all to celebrate the Therian Formes of Tornadus, Thundurus, and Landorus coming to Pokémon GO.
• A Special Raid Weekend event featuring Legendary Pokémon will take place on Saturday, March 27, 2021, through Sunday, March 28, 2021.

Stay tuned for more details on each of these events!

Weekly free bundles
Every Monday in March, a free one-time bundle containing 10 Ultra Balls, 10 Razz Berries, and a Remote Raid Pass will be available in the shop.

Quality-of-life updates
We’re excited to share some updates to Candy XL that will help acquiring this resource in Pokémon GO be more fun and accessible.

• Trading Pokémon will have a chance of rewarding a Candy XL for the Pokémon you’ve traded. The chance of receiving a Candy XL will increase the greater the distance between Pokémon catch locations is.
• Walking with your Buddy Pokémon will now have a chance of earning you a Candy XL.
• Catching Legendary, Mythical, or evolved Pokémon is now guaranteed to reward you with Candy XL.

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/mar-2021-events/?hl=en