Retrieve things from bushes when in slingshot mode etc
Maybe a simple hold x or  to retrieve things from trees and bushes instead of waiting the whole time for a power up timer to run out. Video: https://youtu.be/FddhsKCUrAA This little improvement will definitely improve the flow of things.
Keeping the effects of a present after you die
In the original, if you had a life left, you could keep using the effect of a present as long as the time hadn't run out. This helped a lot when you were having trouble not dying.
Disable Switch Bodies If One Player is Toddler
I love playing this game with my four year old but it's instant death if she opens the swap bodies present. She can't yet read and doesn't know exactly what she's opening but once she grabs control of me on "normal" difficulty, she has no idea what to do. Great present but not for toddler mode.
Unique Agro Behaviors
As it stands, the majority of the earthlings behave the exact same way. Run straight at the player, and that's it. What I'm suggesting is more or less making sense of the earthlings behavior based on their character. Example: The texting dude wouldn't just b-line for the player but instead try and stagger into the players side. Example: having the boogie men be completely invisible so they can ambush the player when in range. More stuff like this would just be a welcomed edition to an already enjoyable game. (Making the original earthlings act like they did in the first game would be a nice touch too.)
3-4 Player Character Selection Screen
Zooms out the character information to make room for up to 4 players since every character has different abilities that should be looked over before choosing them. Could also add some extra UI showing how to join, rather than just "On vacation".
Some songs from game are missing from the official soundtrack
The game has a few tracks not included on the soundtrack that was released. Cody theme without cymbals, the elevator tracks, and a couple additional ones for the hyperfunk zone.