Here is a list of all sprites that are changed as global changes for the hack.
Level specific sprites aren't included. That is, if you have sprites that you want to use in your level, feel free. They just aren't added to this list.
Also, please bear in mind that a lot of sprites on this list are still being worked on.
If you want to contribute to any sprite that's not yet in the list, please use the Sprite Changes topic.
Latest Update
-Added dolphins to list
Not all sprites in here are official yet, but this is so you know that there is at least one suggestion been made.
Characters
Mario -> Demo INSERTED

Yoshi (good guy) -> ?
Enemy Sprites
Banzai Bill -> ? INSERTED
Big Boo -> ?

Blargg -> Yellow Submarine INSERTED
http://www.youtube.com/watch?v=BKE64ZZ5MxI
Bob-omb -> Lightbulb
Bony Beetle -> GooMouse (?)
http://www.youtube.com/watch?v=cxOe5a4oGKA
Boo # 1-> Spy boos INSERTED
Boo # 2 -> Smug boo
Bouncing football -> Baby Yoshi


Bowser Statues -> Frogs INSERTED

Bullet bill (horizontal/vertical) -> Mohawk Bill INSERTED
Bullet bill (diagonal) -> ? INSERTED
Buzzy Beetle -> ? INSERTED
Cheep Cheep -> ? INSERTED
http://www.youtube.com/watch?v=k0e6mH6Hohg
Dolphin -> Genie
DryBones -> DryGoo (?)
http://www.youtube.com/watch?v=cxOe5a4oGKA
Eerie -> ? INSERTED
Fishin' Boo -> Fishing Fish Guy

Flying Hammer Bro -> Octobro INSERTED
http://www.youtube.com/watch?v=uvHVPHfna9Y
Fuzzy -> Neckbeard INSERTED
Goomba -> ? INSERTED
Hopping Flame -> Evil Flame INSERTED
Magic koopa -> Black Mage INSERTED
http://www.youtube.com/watch?v=RjeYy10JJe8
Mechakoopa -> Pumpkin Guy INSERTED
Mega Mole -> Shopping Cart
Monty Mole -> Walking Lips
Munchers -> Yoshi Munchers

Ninji -> ? INSERTED
http://www.youtube.com/watch?v=kThodSbq ... re=channel
Podobo -> ? INSERTED

Pokey -> Donut Pokey
Rex -> Charlie Horse INSERTED
Rip van Fish -> Rip van Chick INSERTED
Saw -> Fork with Spaghetti
Spiney -> Flamey Guy INSERTED
Sumobro -> Kyonshi INSERTED
http://www.youtube.com/watch?v=jpEL-BpX ... re=channel
Torpedo Ted -> ? INSERTED
Thwimp -> ? INSERTED
Thwomp -> ? INSERTED
Wiggler -> Chiggler

Other Sprites
Diagonal Platform -> Lime platform

Dragon coin -> raocoin INSERTED

Note Block -> Tofu Man Note Block
P-Balloon -> Hamburger
P-switch (blue/silver)-> P

Parachutes -> Balloons

Timed Platforms -> Lemon Platforms

Trampoline -> Green Ball
Triangle -> Watermelon

Wooden spikes -> death pencils

Power-ups
Mushroom -> Radish INSERTED
http://www.youtube.com/watch?v=AhnA4M2g ... re=channel
Flower -> Cactus INSERTED
http://www.youtube.com/watch?v=AhnA4M2g ... re=channel
Feather -> Pop-corn INSERTED
http://www.youtube.com/watch?v=AhnA4M2g ... re=channel
Star -> Leek INSERTED

Sprites that still need to be changed:
Enemies: look here and compare with the list
Others:
-What is not yet on the list and you think should be changed.
Things we scratched:
-Mario rex. Mario doesn't quite fit in with the story so far.
IF ANYTHING NEEDS TO BE CHANGED, LET ME KNOW