On the option screen hold select and press A, some more options will appear below the gallery option.
3/18/2001
Super Hard Mode
Highlight ''Hard'', then hold select and press A button.
12/28/2001
Intense Mode
To open up intense mode on challenge, highlight super hard mode then press select+A.
9/18/2002
More Records
While in the record screen, press and hold Select+A and you get more records. Now you can display how much combos, chain you got and how much blocks your cleared.
Make a 10-block combo before fighting Clair on normal or higher level and you'll fight a Pokefan. Defeat him to get his Togepi.
Marill
Make a 4-chain before beating Clair on normal or higher level and you'll fight a swimmer. Defeat him to get his Marill
Pikachu
Make a 6-block combo before fighting Clair on normal or higher level and you'll fight a Gentleman. Defeat him to get his Pikachu.
Sentret
Make a 7-chain before fighting Clair on normal or higher level and you'll fight Beauty. Defeat her to get her Sentret
Bellossom
On normal level or higher, before fighting Clair, defeat your opponent in less than 30 seconds to face Lass. Defeat her and you'll get Bellossom.
Pichu
Play challenge mode on normal or harder. Last for at least 4 minutes on any round before reaching Clair. A Pokefan should challenge you. Defeat her to get Pichu.
10/3/2003
Max. Speed Increase
At the beginning, right when Pikachu smiles, enter: B, A, Left, Left
This will increase the speed drastically if you're on speed 99. Normally, anything at or above 50 will continue at speed 50.
7/10/2006
Disable Stops
When you power on the game, wait until Pikachu smiles, then enter: Left, A, B, Up.With this code, the blocks will no longer temporarily stop rising when you score a chain or combo.