head to head
Neither is simply harder - they are hard in different places. Pokémon Black demands more variance; Portal demands more execution.

Optimization · Pure Optimization
Fifth-generation reboot with an entirely new monster roster and stronger story.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Pokémon Black leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Pokémon Black
Menu battles, zero reflex demand
Portal
Portal placement timing modest.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Pokémon Black
Story trainers follow fixed logic
Portal
No adversary modeling player.
Pokémon Black leans clearly harder on variance.
Pokémon Black
Encounter and damage-roll randomness
Portal
Deterministic chambers; no randomness.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Pokémon Black
All-new dex forces fresh team optimization
Portal
Pure puzzle-solving optimization.
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.