I found this on the Spriters' Resource site:http://www.spriters-resource.com/fullview/31931/
That is the reason I see exactly why Pokemon Puzzle League needs to be hacked, but there are other things too.
If a Pokemon Puzzle League hack were to exist, then these things would be included:
1. First and foremost -- Champion Gary as a playable trainer in 2P mode for both 1P and 2P (his Pokemon are fully evolved)
- Possible code: Simply hold down L+R+Z as you select Gary.
2. The ability to select Pokemon for the Mewtwo stage (Both sides are always forced to play as Pikachu, and after the match, the game does not return to the 2P mode menu -- it immediately starts a new match)
- A custom Pokemon select menu would need to be implemented, and after completion of a full match, the game should return back to the main menu for the selected mode rather than just immediately start a new match.
3. The ability for both 1P and 2P to select the same trainer (would apply to Champion Gary and Mewtwo)
- There is a code that prevents both players from selecting the same trainer. It would have to be removed.
4. Allow a trainer other than Ash to play in the Mewtwo stage
- 1P selects the desired trainer, then inputs the Mewtwo stage code
5. Mewtwo stage reversal (1P plays as Mewtwo, the other plays as Ash/other trainer, and the background would be horizontally flipped)
- Possible code: R+Up+A+Start+A+B+L+Up+B (BULBASAUR code backwards); if 2P desires to play as a trainer other than Ash, then 2P selects the desired trainer, but it works only when the Mewtwo reverse code is used.
6. Mewtwo vs. Mewtwo
- Both players must select Ash and input either Mewtwo code on the Pokemon select screen.
7. Dark blue blocks always on for all difficulty levels of gameplay
- Possible code: B+L+Up+R (input code at main menu). To turn it off, just input A+R+Down+L.
8. Smarter AI for 3D mode in 2P mode
9. 3D mode in 1P vs mode (only if #8 works)
10. Combo icon/garbage block bugs/glitches
- If you throw so much garbage at your opponent, 2P's combo icons at the top left of the screen become buggy and disappear, eventually, you wouldn't be able to throw anything. And when you create a chain of 14 links or more, the corresponding garbage block will be a glitchy block 12 rows high, but would be a normal x12 block when the bottom row is cleared.
11. 3D Puzzles (Another must-have)