I only know bits and pieces, but there will be weekly reveals through the Frebruary 27th, and then additional announcements leading up to the Generation 10 release. Some of the things I know are confirmed to be announced on the 27th include the following:

>Generation 10 titles and a teaser video
>At least five LEGO Pokémon summer sets, along with an animated promotional video
>A new animated theatrical movie announcement, although I do not know the studio, title, or plot details
>More information about the Aardman series

There may also be announcements related to a new anime and an update on the Netflix live-action project later this year, but I am not fully certain about those. I do not have any additional information beyond this.