Press C-Down + R, C-Left + R or C-Up + R at the options screen. Modify the first six bits of a 16-bit register to change the game be pressing:

C-Down + R (head size, alters bits 1 and 2)
C-Left + R (body size, alters bits 3 and 4)
C-Up + R (announcer's voice, alters bits 5 and 6)