>>38311755Dissolve the "friendship group" at the start. You get your starter alongside Calem/Serena and Shauna. Tierno and Trevor aren't encountered until later.
Shauna becomes a mix of Bianca, Lyra, Shauna and Hau. She is friendly and upbeat and every time you encounter her after a city with a boutique she changes her outfit. Her team focuses on cute Pokemon such at Swirlix/Spritzee (opposite of which version you're playing), Furfrou (has a different haircut matching her outfit each battle), Woobat, and Goomy.
Trevor is encountered 4 times, challenging you to his "Pokedex battles" late into the first 1/3, near the middle of the second 1/3, and then at the beginning and end of the final 1/3 of the three different Kalos "regions". Each time you battle him, his team is comprised of local Pokemon, much like N's team is. Also Sawsbuck is added to the Kalos dex and depending on where it's caught it has a different seasonal form. The reason why he challenges you to Pokedex battles is revealed when you encounter him at Team Flare's HQ; he is an admin and has been collecting data on you because you were perceived as a threat. After you beat the game you encounter him again, telling you Flare has dissolved and he is looking to do honest work for the Professor now before asking you for a battle. His postgame team is full of rare Pokemon from all across Kalos.
Tierno is encountered at the obligatory Pokemon Contest tutorial, and all of his Pokemon have full movesets meant to be used in contests, not battles. Examples: Focus Energy+Stone Edge+Force Palm+Smelling Salts Hariyama, Rain Dance+Sunny Day+Weather Ball+Morning Sun Roserade, Defense Curl+Rollout+Rest+Snore Diggersby. The times you battle him he's mediocre, but when you face him in the Master contests, he is brutal. Also when you beat him in the story battles he gives you TMs that require strategy or other moves to use effectively, like Venoshock, Smack Down, Dream Eater and Trick Room.