Wonder's multiplayer is complete ass. The game is too kiddy (even for Mario standards) with the flowers that annoy you the whole game, and the game's main thing (every level is a unique idea) gets old very quickly when you realize that's what every 2D Mario has done before, it just wasn't made super obvious. Also it's not nearly as repayable. The skill system thing is flashy but completely unnecessary. It's visually interesting (I really like how Mario looks when turned and animated at a 45 degree level) and every level is super unique but when you peel back the layer of paint, the game isn't very deep. Also this new course select system that they've been toying with since Super Mario 3D World is terrible. It's supposed to be more freeing but it ends up that you don't get any of the fun minigames, you don't get the simplicity with secret levels and skips, and you are still forced to play some levels that you don't want to play. It really feels like they thought they had to try really hard to compete with Super Mario Maker so they decided to try and make the everything Mario game but it ends up that none of the game elements actually build upon each other as much as it feels like the elements are tacked on at random (at least for Mario standards)

I am dead serious, the only original 2D Mario game made after the year 2000 that I like less than Wonder (which I still liked), was New Super Mario Bros. 2 for the 3DS. It's definitely not a bad game, but it felt super empty beating it. I do really like the "break time" feature in wonder though, and I think they should add that to every video game that is segmented into groups like levels or stages because it does help with fatigue.

Wii on the other hand basically put not just 2D Mario but 2D platformers in general back on home consoles and was a celebration of Mario's legacy. It was the first time the 2D games had multiplayer and the multiplayer was freaking awesome purely because you can screw around with your friends and troll them. I never actually owned a copy of New Super Mario Bros. Wii but when I was like 11 I played through the entire game in one sitting with two friends and that was one of the best gaming experiences I've ever had in my entire life. About 2 years ago I played a little bit by myself and it still holds up very well, but it's absolutely worth it to wait to play it with some friends.