BUR #30540 has been approved by @nonamethanks.
mass update slideshow ~animated ~flash -> -slideshow slideshow_animation
create implication slideshow_animation -> animated
The slideshow tag is almost entirely comprised of animated slideshow posts, so it should be a meta tag that implies animated. There's literally a couple of posts in there that show actual slideshows though, so I'm leaving them alone and making a new, less ambiguous tag for the animations.
The BUR wouldn't let me include a line that changes a non-existent tag's category, so I added the tag to a single post in advance. If this BUR is rejected then that single post can be manually reverted with ease.