Originally Posted by Fat Focus
Does Leech Seed decrease the infected Pokémon's health if the opponent's side has no recipient for the healing effect? I am asking this because my seeded paralyzed guts Roobushin @ leftovers did not lose any health due to Leech Seed the turns that it knocked out an opposing Pokémon, and I was wondering if this is part of Leech Seed's effect or a PO glitch. Bulbapedia says that this is no glitch, but Smogon's description of Leech Seed makes no mention of this mechanic. I would like for this to be cleared up. Thanks!
This has been in every 4th and 5th gen game I think. To answer your question, yes, if there is no recipient, leech seed will not take any health. This was a change that occurred in the newer games (as in, for example, 3rd gen, you would switch when a pokemon fainted, not at the turn's end; in DP and on, you switch at the turn's end and thus go after leech seed).