I work in Niantic’s marketing team. Not going to confirm whether it’s the graphics team or social media or any of thay for obvious reasons. Working here has allowed me to find out lots of info that’s currently unreleased to the public, including details of future events, such as the Hoenn Festival, Spring 2019, and a few more unnamed ones that haven’t fully been developed into their concept yet. Anyways here’s the juice:

Hoenn Festival:
- Increased spawns of Hoenn Pokemon
- New raid bosses based off
Hoenn Pokemon. I know the starters will be tier 1s, and Flygon will be a tier 4 boss. Latios and Latias will make a return in their shiny forms.
- Shiny Pokemon put forward to marketing are shiny Lileep and Anorith. This doesn’t mean there will be more shiny Pokémon, however.
- Clampearl will be released into the wild as well.
- Regional mixup will be included with this event as well. Don’t have any details but it seems like it will be Illumise and Volbeat based off promo art.
- Jirachi special research will be released.

Chinese New Year:
- Boosted pig spawns, including shiny Swinub and Spoink. Double dust upon catching.
- Around here is the time the Lake Trio is released. In raids. Niantic is abandoning the whole regional boss thing if you can’t tell.

Dragon Festival:
- Increased dragon spawns, like Dratini and Bagon.
- Shiny Horsea will be released.
- Palkia and Dialga will come to Raids.
- During this month Bagon CD will occur, sort of like a tie in with the event.
- Shiny Rayquaza will be released on a raid day toward the end of the event.

Spring 2019:
- This is not the official name of the event. It will start around the beginning of March.
- Shaymin special research will be released. Sky Forme will be a T4 boss.
- Fire/Grass/Ground types will be increased with double candy.
- Plenty of Sinnoh Pokemon will be released, as well as the rest of the evolutions. Such as Wormadam, Cherubi and Shellos.
- Don’t know what shiny will be.