I think lvling will be slower than pokemon white/black 2
What most people didn't reliease is that inn the hollow tree challenge you could sort off skip the trainers and just look for breeder kind trainer who had chanseys who gave a TON off XP + The breeder bug where they will keep fightning you over and over inn the stadium, so you could farm rare candies.
Thoes 2 things, aswell as Audino's made lvling so easy...Cant imagine Y / X is faster.