Replacing Enemies, and other sprites

So I am wondering if it is possible to replace the sprites of enemies and springs and eggman and spikeballs and everything else models can replace, i just need it for a project, would i need a P_SKIN? or would i need something else

You would need to put the graphics in between S_START and S_END lumps in a WAD, or in the Sprites\ folder in a pk3 like so:
Of course, these examples use the Crawla sprite name for reference. Also, there was a wad that did just this with the Pointy enemy, you could open it up in SLADE and see how it works.

okay thx u