head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is execution, and it is a single point.

Optimization · Pure Optimization
Lane-defense economy optimization against semi-randomised zombie waves.

Optimization · Pure Optimization
Team building and type-matchup optimization through a scripted island campaign.
Plants vs. Zombies 2: It's About Time leans Optimization (Pure Optimization); Pokémon Moon leans Optimization (Pure Optimization).
Plants vs. Zombies 2: It's About Time leans a little harder on execution, though the gap is small.
Plants vs. Zombies 2: It's About Time
Tapping plants quickly only matters in surge moments
Pokémon Moon
Turn-based menus require no dexterity
Pokémon Moon leans a little harder on reads, though the gap is small.
Plants vs. Zombies 2: It's About Time
Zombie waves are announced patterns, not minds
Pokémon Moon
Scripted trials and trainers; competitive play is a niche mode
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Plants vs. Zombies 2: It's About Time
Wave compositions and plant-food drops add per-level randomness
Pokémon Moon
Encounter tables, catch rolls and crits are mappable RNG
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Plants vs. Zombies 2: It's About Time
Lawn economy and plant placement are the solvable core
Pokémon Moon
Team composition and type math are the solvable core
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.