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
Handheld tactics RPG adding a shifting law system to grid battles.

Optimization · Pure Optimization
Plannable type-matchup progression through two regions of fixed trainers.
Final Fantasy Tactics Advance leans Optimization (Pure Optimization); Pokémon SoulSilver Version leans Optimization (Pure Optimization).
Final Fantasy Tactics Advance leans a little harder on execution, though the gap is small.
Final Fantasy Tactics Advance
Turn-based grid commands only
Pokémon SoulSilver Version
Menu-driven battles have no physical component
Pokémon SoulSilver Version leans a little harder on reads, though the gap is small.
Final Fantasy Tactics Advance
Scripted opponents, judge rules are fixed
Pokémon SoulSilver Version
Trainer AI is scripted; human battles are an optional sideline
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Final Fantasy Tactics Advance
Random laws and hit rolls
Pokémon SoulSilver Version
Catch rates, crits and encounters are bounded randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Final Fantasy Tactics Advance
Race-job ability combos reward deep planning
Pokémon SoulSilver Version
Team building against known gyms is fully plannable
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.