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

Optimization · Pure Optimization
A calendar-driven JRPG carried by persona fusion and social-link planning.

Optimization · Pure Optimization
Building a team and exploiting type-matchup math against scripted trainers.
Persona 4 Golden leans Optimization (Pure Optimization); Pokémon LeafGreen Version leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Persona 4 Golden
Turn-based, no input demand
Pokémon LeafGreen Version
Menu-driven turn battles demand no physical skill
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Persona 4 Golden
Scripted enemies
Pokémon LeafGreen Version
Trainers are scripted; link battles are a side mode
Pokémon LeafGreen Version leans a little harder on variance, though the gap is small.
Persona 4 Golden
Weakness and crit rolls
Pokémon LeafGreen Version
Wild encounters, catch rolls and crits add mappable RNG
Persona 4 Golden leans a little harder on optimization, though the gap is small.
Persona 4 Golden
Persona fusion and calendar routing rewarded
Pokémon LeafGreen Version
Type matchups and team building 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.