Yeah I don't really know how to hack into the graphics either, I can't figure out SNES decompression and it's one of those subjects that, when you look it up, you just find discussions of people who know not necessarily giving very much detail to people who don't). But, no matter, all you really have to do to see the graphics is to download VSnes, play the game in Snes9x or ZSnes up to the point where the sprites you want appear, save state, and open that state in VSnes. There, you can open the Scene Viewer and Memory Viewer windows. In Memory Viewer is where you actually see the sprite "sheets", everything is a little jumbled because, as you may know, there are top halves and bottom halves and stuff for the characters and some sprite frames are simply flipped during gameplay. You'll have to check the WRAM or ROM radio buttons on the Memory Viewer to see the real sprites. Then you've got to have the right palette, so using Scene Viewer, select the top tab "layers", the second-to-top tab "sprites", and mouse over what you want (for example, player one as Bomber the Kid); the PalViewer window will automatically switch to that sprite's palette (they are arranged in rows), take note of which one it is and if you accidentally mouse over a different sprite you can just select the right palette in PalViewer. With the right colors, you should see the sprites as they're supposed to be.
But if you think this is interesting... check this out, that I found today!:
Unused Neo Bomberman sprites! The colors are, I'm sure, all off, but since these sprites never appear in-game I had no palettes to work with. Ripped with WinKawaks. Firstly you can see traditional Bomberman mug shots, normal, winning, and defeated. These were replaced with tiny heads at the top of the screen and, on the score board, just big heads that never animated. But take note of the characters... Shiro is there, but also Pretty Bomber (I just chose the palette that made her shading look right), who only appeared in cutscenes in the final game, two alternate versions of Cat Bomber (guess they hadn't decided yet), Fake Bomber, an old design of Hayate Bomber (I personally find this one very interesting, his face was going to be that of a normal Bomberman!), an unnamed Bomberman wearing what appears to be Chaos Bomber's armor (from Bomberman Quest), Rubber Bomber, Atomic Bomber, another unknown Bomber who appears to be Hero Bomber (though I could be wrong, I don't have the actual palette), and an alternate design of Atomic Bomber (with white eyes).
Underneath these are some totally random sprites of what I can only guess is a monkey with a hat and a drum (it also has a smile on its face if you check with different palettes), and the Battle Mode final victory image of Atomic Bomber's alternate design... what is up with the protrusion from his forehead? O_o
Now that I think about it, there may have been an unused ridable monster somewhere near the beginning of the tiles. But yeah, these are all very interesting to me. Why'd they nix those two extra Bombers and just put in Honey and Kotetsu instead? And remove Pretty Bomber (I'm guessing that is why we see Honey using Pretty Bomber's floating bomb, she must've been the replacement), and seriously, what is up with Chaos Bomber's emblem appearing on that unused guy?