Palkia, the water dragon is here! It’s going to be a good addition to your PvE raid squad, and you want that shiny. It doesn’t see much use in PvP, probably cause Dialga and all.
The dual typing only leaves dragon and charm for super effective damage, and dragons just have too much power to be stopped. Lucky there aren’t many community day moves you need, and it’s a good time to use the Latios and Latias we had in raids not that long ago!
Go to the official counters page for a complete list including Shadows and Megas to see how your Pokemon perform.