New Championship Battle mode online lets you battle with VGC 2017 rules - doubles with no mega evolution. Only Alola Pokedex Pokemon obtained in Sun and Moon can be used.
A chess timer is also an option, called "Your Time". Players have 60 seconds per turn as well as 10 minutes of "Your Time". If you run out of your time, you lose. This squashes timer stalling tactics - previously, the match timer was shared between players, and if the timer ended, the player with the healthiest team won. This allowed players to stall out the timer if they knew they could keep their team healthier. Many disliked this tactic, and clearly the Pokemon company agree.
A chess timer is also an option, called "Your Time". Players have 60 seconds per turn as well as 10 minutes of "Your Time". If you run out of your time, you lose. This squashes timer stalling tactics - previously, the match timer was shared between players, and if the timer ended, the player with the healthiest team won. This allowed players to stall out the timer if they knew they could keep their team healthier. Many disliked this tactic, and clearly the Pokemon company agree.