head to head
Neither is simply harder - they are hard in different places. Borderlands 2 demands more execution; Pokémon Trading Card Game Pocket demands more reads.

Optimization · Systems & Chaos
Loot-shooter RPG built on gear chasing.

Variance · Systems & Chaos
Streamlined card battles where deck construction fights the coin flips.
Borderlands 2 leans Optimization (Systems & Chaos); Pokémon Trading Card Game Pocket leans Variance (Systems & Chaos).
Borderlands 2 leans clearly harder on execution.
Borderlands 2
Aim matters but generous hit feel
Pokémon Trading Card Game Pocket
Tapping cards takes no skill
Pokémon Trading Card Game Pocket leans clearly harder on reads.
Borderlands 2
Enemies are scripted loot fodder
Pokémon Trading Card Game Pocket
Human opponents exist but the simplified format limits bluffing depth
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Borderlands 2
Procedurally generated weapon drops vary
Pokémon Trading Card Game Pocket
Coin flips, draws and pack pulls dominate single games
Borderlands 2 leans clearly harder on optimization.
Borderlands 2
Skill trees and gear math heavily solved
Pokémon Trading Card Game Pocket
Deckbuilding around a small card pool is quickly solvable
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.