A player controlling this monster loses 300 Life Points during each of his/her Standby Phases when this card is face-up on the field. Control of this card is shifted to your opponent by paying 500 Life Points at your own End Phase.
Rulings
Netrep Q&As
Q: When you give control of “Mushroom Man #2” to your opponent, can your opponent use its effect during their turn to give control back to you? A: Yes they can. In this way the “Mushroom Man #2” can have control passed between the two players for multiple turns by paying the 500 Life Point cost during their End Phase. Curtis Schultz, 12/10/2003