The aimed native resolution these graphics are made for are:
320x180 px (1/6th of full HD)
480x270 (272) px (1/4th of full HD)

if you need more information on resolutions here is a chart:
https://www.deviantart.com/cyangmou/art/Pixel-Gameart-101-06-Pixelart-Screen-Resolution-688071910

Most of the animations are created with having a basic framerate of 10 - 16 fps in mind (that's 60ms - 100ms per frame)
The gal files are set to a speed of 60 ms / frame

The slime is designed in a way that all loops can be played.after each other.
The defence stance is meant to be hold.

Tilesets are seperated into: tilesets, gms2 tilesets and add-ons
tilesets - those are the basic tilesets, containing all normal tiles
gms2 - those follow YoyoGames GameMaker Studio 2 autotile setup and can be used with the engine.
add-ons - in case you don't use GameMaker Studio 2, the add-ons provide the same tiles as the gms2 tilesets, but sorted in a different way, which might be easier to use. The templates are delivered for a clearer usage.

More assetpacks in the same series can be found here:
https://itch.io/c/880983/8-bit-side-scroller-series-by-cyangmou

In the lights assetpack there are a ton of lights, off states and destructed versions as well as particles which will work with this assetpacks lights:
https://cyangmou.itch.io/8-bit-side-scroller-animated-lights

Graphics Gale can be downloaded for free here:
https://graphicsgale.com/us/