There were leaks in the recent past that outlined what may be included within the new raid updates. They included plenty of visual changes and the now-announced Trainer Achievements. Though visuals weren't discussed much by Niantic in their blog post, Trainer Achievements had more detail.
Slated for release this summer in Pokemon GO, Trainer Achievements are meant to help "celebrate trainers" within raids. Essentially, completing a certain objective while in a raid will get a player showcased at the end of the battle. A list of some of the feats that players could earn while in raids was given on the blog.
Trainer Achievement feats in Pokemon GO
- Delivering the final attack
- Dealing the most damage overall
- Keeping a single Pokemon in battle for the longest time of all participants
- Using the tallest Pokemon among all participants in battle
- Joining the raid from furthest distance
- Using a Mega-Evolved Pokemon during the battle
- Changing your avatar’s clothing or pose
- Using the most Charged Attacks of all participants
When players earn a feat or a Trainer Achievement, they will be rewarded in bronze. They can all eventually be leveled up to silver and gold, which can then be displayed with avatars.
Pokemon GO raid visuals along with Trainer Achievements
Like the Trainer Achievements, raid visual changes are set to release in the summer. Though the details are more scarce, there were at least some outlines confirmed in the blog post.
There will be art and UX updates for the raid stadium, many of which have already been leaked. Nothing concrete has been confirmed, but it may include crowds, small screens in the stadium, and team banners throughout.