Finish Substitute Implementation

[Ericzklm]

I've hastily added some logic for Substitute in order to have the calculations correct for baby strat

• What should already be implemnted:
  • Substitute subtracting HP if > 25%
  • Substitute's own HP counter
  • Substitute absorbing damage including damage beyond substitute's health
• What's possibly missing
  • Handling stat lowering + status blocking
  • Moves and abilities that bypass substitute
  • Interactions involving further testing (ex. what happens on Fling)