@ Nightshadow: Perhaps we could make an exception for something as badass as Tyranitar? =)
@ Jason 137: They refer to effects that have a given probability of happening but occur more often than they should. In the Battle Tower these frequencies tend to be biased in favour of the enemy team.
- Critical hits have a 1/16 chance of happening, the AI this triggers more often (whereas you do not).
- Quick Claw is an item that has a 20% chance of making your Pokémon attack first, the AIs activation is higher than that.
- Brightpowder is an item that can cause your opponent to miss attacks, same story.
- OHKO moves have a 30% chance of hitting, the AI hits them at least half of the time.
As for Encore, it seems like a valid strategy to abuse but unfortunately it only lasts for a couple of turns. This makes it harder to base a team around it than a Trick team, though I suspect it could work.