I've unlocked Challenge mode by beating the champion in Black 2. If I unlock it for a friend what changes exactly? Bulbapedia wasn't very specific, just mentioning that the AI becomes more challenging, higher level Pokemon, and more held items.
- Are the changes universal or limited to mostly important NPCs (gym leaders, Team Plasma leaders etc)?
- How does the AI improve? Does it swap Pokemon more often or is it mostly better move choices?
- Are all the Pokemon in the game higher level or just the trainers you battle throughout the game?
- What sort of held items does it unlock for the enemy? Does it increase the chance of wild Pokemon having a held item?