The two JoyCon controllers on either side of the Switch are detatchable; each one can function as a simple controller for most games on the system. So, for multiplayer, each player can take one and go nuts with it. They both have decent motion controls, one has an IR scanner, good vibration, little speakers, etc. – basically a hyper-miniaturized Wiimote with worse motion-accuracy.
The individual main-line Pokemons are usually split into 2 or 3 versions with a handful of unique Pokemon, gym leader bosses, and quests for each variant; you need to connect with pals via local or internet multiplayer to get the stuff not in your game. But your kid made the right call; the unique stuff in Shield is cooler :)
Simple, but cute multiplayer; the second player control the little hat companion that can collect coins and bop enemies, IIRC. Sorta like the MP in Galaxy, if you played that.
Excellent local or online multiplayer, absurd amounts of content for the price (it’s basically an upgraded version of the Wii-U version + all of its DLC).
Awesome, charming, relaxing, very sweet and silly building-and-friendship game. The multiplayer has a couple of weird quirks. First and foremost, whoever makes the first Villager character for the game on a given console is the “Island Representative,” who controls the progression of some of the game content, so if they make a character and abandon the game, Player 2 is stuck with basic tools and housing forever. Once you make it past the couple-few weeks of starter “quests” on the island, everything is more or less unlocked for everyone.
Mario Party for Switch only has a few boards, but they’re all good, and the minigames are great. Only allows Joycons for play – no Pro Controllers here, folks! But they have lots of fun and funky motion oriented games and stuff that uses the microphones, IIRC, so if they dug the Wii version, they’ll probably like this, too.
A word on online MP: You do need to buy annual access to Nintendo Online. It’s very cheap compared to XBox Live and whatever Playstation has, and comes with while-subscribed access to big libraries of emulated SNES and NES games. Also supports online backups of most game saves and a few other neat features.
By default, the MP is tied to one system profile (Switch supports multiple user profiles, so multiple people can maintain saves/characters in the same games on the same system – see above for the Animal Crossing stuff on that). If you only run one main account, you’re good. Otherwise, spring for the Family Plan, which is honestly just a few bucks more. If online MP isn’t a big deal, this is totally skippable, though.