In a Two-Headed Giant game, life gained by your teammate won't cause MJ, Rising Star's ability to trigger, even though it caused your team's life total to increase
Minnies abilities tie in nicely with his own, as well as with other cards with inexpensive gain strength abilities that may have been overlooked previously
Then each creature that isn't an Insect, Rat, Spider, or Squirrel gets -1/-1 until end of turn for each creature you control that's an Insect, Rat, Spider, or Squirrel
In short, as many as your cards allow you to
the card is just too bad in the fair games where it is hard to spend a whole card just to bounce an opposing spell back to hand for a bit
Victory is for losers