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

Optimization · Pure Optimization
Solvable type-matchup and team-building math across a scripted adventure.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Pokémon Alpha Sapphire leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Pokémon Alpha Sapphire
Turn-based menus, zero physical ceiling
Portal
Portal placement timing modest.
Pokémon Alpha Sapphire leans a little harder on reads, though the gap is small.
Pokémon Alpha Sapphire
Campaign trainers are scripted; PvP is optional endgame
Portal
No adversary modeling player.
Pokémon Alpha Sapphire leans clearly harder on variance.
Pokémon Alpha Sapphire
Encounters, abilities and catch rolls add mappable RNG
Portal
Deterministic chambers; no randomness.
Portal leans a little harder on optimization, though the gap is small.
Pokémon Alpha Sapphire
Type math, breeding and team building are the core
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.