So say If I wanted all my Magikarp's and Diglett's moved from Box 1 into box 26, I'd like Shift click them all, go over to box 26, There would be a highlight of how many boxes you need while Holding Shift It'd be Green if there was enough room and Red if there wasn't, If it was Red it won't let you move em, Green will put them where the outline is.
Another part of this would be to remove a bunch of Pokemon you don't need, If you tried to remove a group of Pokemon, It'd say "Are you sure you want to remove *Number of Pokemon*?" and you'd press accept then your PC is cleared. I personally think this is better than removing 1 by 1.
I know this isn't a big feature, so it's kinda hard to explain, but I would love if it got recognition and consideration, I spam breed my Pokemon and have a hard time getting them into the right boxes or getting rid of them in general.