Capcom vs. SNK: Millennium Fight 2000 cheats and cheat codes for Dreamcast

Unlock EXTRA characters
Finish arcade mode with a fighter to unlock their Extra form in 
the hidden shop. Go to the shop and buy, then enter to the 
fighter selection screen. While selecting your fighter, hold Start 
to change to "EX" character. While still holding Start, hit 
A, B, X, or Y to select that fighter.

Unlock Secrets 34 (Evil Ryu) and 49 (Evil Iori):
Finish both the SNK and Capcom grooves in arcade mode with "Normal" Iori 
and "Normal" Ryu. Go to the hidden shop and buy them for 7,000 versus 
point seach.

Gouki (Akuma) as opponent:
First unlock and buy  Gouki's Shadow (secret 62) in the hidden shop. 
You have to pay 500 versus points. Reach 80,000 groove points to 
select them before the start of the last fight.

Unlock secret 71 - Pair match mode
Beat Morrigan and Nakoruru in arcade mode then buy Pair match mode 
for 1200 VS point.

Unlock secret 69 - Gouki's (Akuma) stage.
Beat Gouki in arcade mode on the SNK groove, then buy 
Gouki's stage for 1500 VS point.

Unlock secret 68 - Nakoruru's stage
Beat Nakoruru in arcade mode then buy Nakoruru's stage for 1200 VS point.

Unlock secret 67 - Morrigan's stage
Beat Morrigan in arcade mode then buy Morrigan's stage for 1200 VS point.

Unlock secret 72 - Adjustable ratios in VS mode
Beat Gouki in arcade mode on the Capcom groove then buy Adjustable ratios 
for 1500 VS point.

Earn 999 vs. points for the hidden shop:
Enter to training mode, select your fighters and opponent. Enter to battle 
screen, do not fight just leave the game at least 3 hours. You will get 
about 999 vs. points. Repeat as many times you want.