Smogon: We have decided to ban the item Sceptilnite from SM OU. With a blazing fast 145 speed, and with the new buff Mega Evolution turn order has received, Mega Sceptile can nulify any move an enemy throws at it. With a grand total of 8 Pokemon outspeeding it, as well as most of them being in the Uber tier, the only viable pokemon that outspeed it are Mega Alakazam and Mega Aerodactyl. One can say that priority like Ice Shard and Prankster Tauntcan shut down Electrify, but simply having a Tapu Lele or another Psychic Terrain user removes this tactic for about 5-8 turns, which gives Mega Sceptile enough time to set up and start a sweep.
When being forced to carry multiple priority/prankster users and a MegaZam/Megadactyl simply to deal with one pokemon, it is the very definition of overcentralization and Mega Sceptile is extremely unhealty to the meta game. This ban is effective starting immediately.