Assets I made for a practice project following the TileVania course on gamedev.tv. The tiles are 32 x 32, and the player and slime animations are 64 x 64 when you're slicing them up in engine. 

For the parallax: I followed Adam Younis's tutorial for parallax backgrounds on YouTube. The farthest backdrop panel is parallax bg 0, the farground layer is parallax bg 1, and the nearground layer is parallax bg 2. It uses the same naming convention as the tutorial, so feel free to look there if you aren't sure what's going on with the parallax files.

For the slime attack: the animation shows the slime spitting something, and in my implementation I chose to use a game object with the acid bubble sprite on it, as well as a particle system using the acid bubble to create this bubble cluster.