My suggestion is this: allow Dynamaxing and Gigantamaxing outside of battle provided the pokemon has consumed at least one dynamax candy. From there, it'd be another option on the field move wheel. Some notes:
This would allow us to view the intricate & cool models yall have from in game by flying around our max pokemon.
Maybe even Max versions of the existing field moves (such as Max Dig carving a much larger area at once but having an incredibly long cooldown.)
After using a Max Move, the pokemon would revert to their usual form with a cooldown before dynamaxing again, to prevent it being too OP.
Of course, these features would probably need to be optionally disabled from config for servers. Some may not appreciate giant pokemon swallowing the spawn area whole.
From there, the next suggestion: Gigantamax mons being mountable!
-They'd be faster than their base forms, like a "Max Fly" or "Max Surf".
-Multiple people could "hitch a ride" on the pokemon. This could be fun, like GMax-Orbeetle having multiple people spinning around in it's abduction beam and GMax-Lapras having people hang out like it's a cruise ship.
-An alternate to this could be making a mounted gigantamax a bit... solid? So to speak. Like players could stand on the back of them. I'unno if that's possible, but it'd be cool.
Anyways, that's bout it.