In this folder, you should find eight .bin files.  Open these with YY-Chr. (Or whatever other tile editor of you use)  Say you want to change Buzzy Beetle's walking graphics from the version I've included in the game.  You extract the graphics using the red mushroom in Lunar Magic, then open "GFX04.bin".  Open "misc.bin", copy the two alternate Buzzy Beetle frames, then paste them over the top of the ones in GFX04.  Save and reinsert the graphics by hitting the green mushroom in Lunar Magic.  If you're setting up graphics for the custom sprites that come with spritetool, that involves ExGfx, which I don't feel like explaining.  There are tutorials out there.

Here's what's included:

An alternate Peach set that's closer to her Mario Party Advance look.  Peach's graphics are spread out across a bunch of GFX files.  I've labelled where they go, but you'll need to figure out where to paste what.  I trust you can figure it out.

Alternate Reznors.  The ones I have in the game are more triceratopsy, while these are just the original SMW ones with better shading.

An alternate Sumo Bro.  This is a Hammer Bro with a spiked helmet, which seems kind of unnecessary now that Sprite Tool's come and actual Hammer Bros. are available.

Bloopers to replace Rip Van Fish.  Either facing the camera or 3/4 view, and you can use Tweaker to change Rip Van Fish's palette to grey if you wish.

Brick Animation.  If you want to replace Turn Blocks with Breakable Bricks, here are the graphics for it.

The Giant Enemies available with Sprite Tool.  Three varieties of Giant Piranha, optimized for a green palette, a red palette, and a green lipped version.  Also, Giant Goomba, Giant Spiny, and Sledge Bros.

Shy Guys that are optimized for various palettes.  You could use these for the Shy Guy custom sprites that come with Sprite Tool, or you could go old school and just graphics swap them for Shelless Koopas.  (That's what the various sliding and squished poses are for)

Miscellaneous:  An alternate Buzzy Beetle, two alternate Thwimps, a classic squishable Goomba, an alternate Fishbone, a Snifit, an alternate Swooper, two looks for Birdo with two kinds of eggs, an alternate Fishin' Boo, White-lipped Piranhas, Venus Fire Trap, and Hammer Bros.  

The Hammer Bros are 16 x 32, while the ones that come with spritetool are 16 x 24.  To use these graphics, you're going to have to edit the Hammer Bros' .asm file slightly.  Go to the "sprites" folder in your spritetool directory and open "hammer_bro.asm" with Notepad.  You want to find the line that starts with TILE_SIZE and change $02,$00,$00 to $02,$02,$02.  Then change all the $08's into $00's on the line that starts HORZ_DISP and the one beneath it and change the values for VERT_DISP from $F8,$08,$08 to $F0,$00,$00.  You'll also need to edit the tilemap to wherever you want to stick the tiles.  If you were going to stick the Hammer Bro graphics over the top of Rex, for instance, you'd edit the first line of TILEMAP to look something like this:  $8A,$AA,$AA,$00, where $8A would be the head and $AA would be the body.  And then you'd do the other three frames in a similar manner, replacing the body with a new value on each line.
