Demo of WWG is out on Euro eShop and of the small amount of available microgames (ones from the old games and others new) in the demo are Nintendo references.
G&W Manhole, use the d-pad to cover the holes and prevent anyone falling (NEW)* Dr Mario, tilt the system to guide the megavitamin to clear the line (NEW)* Nintendo Switch Joy-Con attaching, use the touch screen to slide the JC on to the Switch (NEW)
*Checked the cameo list for Mega Microgame$ and Twisted and they aren't based off any of those 9-Volt Nintendo microgame cameos, so they must be brand new.
There will be returning cameo games like TWW, OoT and Animal Crossing from Smooth Moves from promo images while Mario wiki has an even bigger list. Just remember beware of spoilers. www.mariowiki.com/WarioWare_Gold
From Super Mario Wiki, in the WWG version of Gamer, the Wii U replaces the Virtual Boy on 9-Volt's shelf. While also gaining more Nintendo hardware (GCN and SFC consoles, N64 controller) in the shelf underneath it. 9-Volt also appears to be using a 3DS (which version?) instead of the fictional gaming device from Game & Wario.
There's also a Fire Emblem game now, first time despite IS's involvement in the series.
Pushmo too. I was under the assumption that this didn't happen before because of the different contract models IS worked under. They hold rights to some games (Panel de Pon, Pushmo…) but not others (WarioWare, Band Brothers P…), so technically having IS assets in WarioWare would require additional arrangement.