Cheren puts different items on his pokemon each time you battle him(almost every time). Same thing with Bianca.
1.When you battle Cheren at the trainer school at Straiton City he has a oran berry on Snivy, Tepig and Oshawott.
2.The battle at route three, they still have an oran berry.
3.Route 4 they have a sitrus berry.
4.Route 5 they have still have a sitrus berry but now their pan/sage/sear/pour have miracle seed, charcoal, and mystic water.
5.Route 7 the evolved starters now have leftovers. Simi/sage/sear/pour still have miracle seed, charcoal, and mystic water. Liepard has a sitrus berry. Unfezant has Scope lens.
6.Route 10, they have the same items as Route 7.
7.The final evolution starter now have focus sashes. Haxorus has a dragon gem. Unfezant still has scope lens. Simi/sage/sear/pour still have miracle seed, charcoal, and mystic water. Liepard still has a sitrus berry. Finally, Gigalith has leftovers.