To give the fighters 255 seconds of time:

POKE AEF9,FF

This changes the value which is written to Time when a game begins.

AEF8	LD A,1E
AEFA	LD (9CA5),A

POKE AD2C,nn

This alters the check ("compare") for how many points 1UP has when a round finishes to determine whether the match is over.

AD2B

CP 04

POKE AD33,nn

This alters the check ("compare") for how many points 2UP has when a round finishes to determine whether the match is over.

AD32

CP 04

POKE 9057,C9

This changes the block of code which handles CPU scoring from:

9057	LD A,(AA48)
905A	AND A
905B	RET Z

To simply just return.

9057

RET

POKE AD4E,10

AD4D

JR Z,AD51

TBC.

This changes:

AD82

AND A

To:

AD82

XOR A

TBC.