"Some of you may be aware of a strategy going around that can force battles to continue indefinitely. This involves using Leppa Berry with Heal Pulse, Recycle, a healing move (such as Slack Off or Soft-Boiled) and Block/Mean Look/Spider Web. Fortunately only Slowpoke, Slowbro, Slowking, Blissey and Smeargle are legally able to use this combination (Ralts, Kirlia, Gardevoir and Gallade as well if you count Wish). To use the strategy, one of these will switch into a defensive Pokemon, or one unable to 2hko them, use Block and then PP stall the opponent with recovery and Leppa Berry + Recycle. Once the opponent begins to Struggle, the user can simply continue to Heal Pulse, with Leppa Berry + Recycle, until the opponent forfeits. An example can be seen here." - Smogon
Here is the link to the full article. http://www.smogon.com/forums/threads/endless-battle-clause.3495355/