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

Optimization · Pure Optimization
The direct Unova sequel with an expanded Pokedex, Pokemon World Tournament, and the toughest Gen 5 content.
Persona 4 Golden leans Optimization (Pure Optimization); Pokemon Black Version 2 leans Optimization (Pure Optimization).
Persona 4 Golden leans a little harder on execution, though the gap is small.
Persona 4 Golden
Turn-based, no input demand
Pokemon Black Version 2
Turn-based; nothing for the hands
Pokemon Black Version 2 leans a little harder on reads, though the gap is small.
Persona 4 Golden
Scripted enemies
Pokemon Black Version 2
Campaign foes are scripted; competitive PvP optional
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Persona 4 Golden
Weakness and crit rolls
Pokemon Black Version 2
Encounter and catch RNG plus hidden IVs
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Persona 4 Golden
Persona fusion and calendar routing rewarded
Pokemon Black Version 2
Deep team building, EV training, and matchup mastery
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.