Two moves in Pokemon Sun and Moon have been banned from online play due to a game crashing glitch

The ban is temporary until Game Freak provides a fix

Just over a week into the launch of Pokemon Sun and Moon, some trainers have encountered a game crashing glitch during online play. Two moves, Memento and Parting Shot, cause the game to crash during online battles when the Z-Powered versions of the moves are used. For now, Nintendo has banned the use of the move until developer Game Freak provides a patch. 

Memento is a high-level move that causes the user to faint upon use, but in return, it harshly lowers the attack and special attack stats of the opposing Pokemon. Parting Shot is a non-damaging move, known exclusively by Pancham and its evolved form, Pangoro where the user lowers its enemy's Attack and Special Attack stats before switching out with another Pokémon in the party.

The glitch affects only the online portions of the Battle Spot including Free Battles and Rating Battles. You are still safe to use the moves in the game's single player mode.

Source: [Serebii via VG 24/7]