Balloon Fight GB:RAM map
Many of these addresses may also be the same in Balloon Kid.
C007: Stage map cursor
D101: Can affect state. When 05 player always has a Power-Up Balloon's effect (thanks nolberto82)
D111: Number of balloons inflated (thanks visitntX)
D117: Invincible if stays at 1B (but does not knock out enemies)
D141: Balloons automatically come back if 01
DE13: Current stage