If Ninjago had guns: No effects on the Skeletons, Stone warriors, Nindroids, Nadhakan, the Oni, Vangelis' army and the Red Visors, but it would deal with the Serpentine pretty quickly 😂. Chen would have been shot by Garmadon a LONG time ago, Wu would no-scoped Acronix. Cole and Zane would have cleared out Laughy's in no time and the events of Hunted and MoTO wouldn't have happened. Aspheera and her army would've been killed off along with Vangelis at his weakest. So would have Kalmaar and his army, which means Wojira wouldn't have happened and Crystalized wouldn't have happened since Harumi would've been put into prison either way (since Hunted didn't happen). In short, it was probably a good idea not to give guns to the Ninjago Police Force.