head to head
Neither is simply harder - they are hard in different places. Super Mario Odyssey demands more execution; Wii Play demands more reads.

Execution · Pure Mechanics
A 3D platformer whose joy lives in tight movement and capture-driven traversal.

Execution · Pure Mechanics
Nine pointer-driven minigames bundled with a Wii Remote, from duck-hunt shooting to table tennis.
Super Mario Odyssey leans Execution (Pure Mechanics); Wii Play leans Execution (Pure Mechanics).
Super Mario Odyssey leans clearly harder on execution.
Super Mario Odyssey
Precise platforming and capture-move tech ceiling.
Wii Play
Pointer aim and timing carry shooting and ping-pong games
Wii Play leans clearly harder on reads.
Super Mario Odyssey
No adaptive opponents whatsoever.
Wii Play
Two-player duels add slight mutual prediction
Wii Play leans a little harder on variance, though the gap is small.
Super Mario Odyssey
Almost no randomness in level design.
Wii Play
Find Mii crowds and target spawns randomise lightly
Super Mario Odyssey leans clearly harder on optimization.
Super Mario Odyssey
Moon routes and movement tech learnable.
Wii Play
Minigames are too shallow to deeply optimise
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.