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.

Execution · Competitive PvP
A party platform fighter testing scramble execution and couch-rival prediction.

Execution · Competitive PvP
Arena fighting built on baiting substitutions and timing punishes against humans.
Digimon Rumble Arena 2 leans Execution (Competitive PvP); Naruto Shippuden: Ultimate Ninja Storm 3 leans Execution (Competitive PvP).
Digimon Rumble Arena 2 leans a little harder on execution, though the gap is small.
Digimon Rumble Arena 2
Smash-style movement and attack timing in chaotic arenas
Naruto Shippuden: Ultimate Ninja Storm 3
Substitution timing and combo confirms need decent hands
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Digimon Rumble Arena 2
Couch opponents bait digivolutions and punishes
Naruto Shippuden: Ultimate Ninja Storm 3
PvP revolves around baiting substitutions from human opponents
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Digimon Rumble Arena 2
Item and power-up spawns shuffle fights
Naruto Shippuden: Ultimate Ninja Storm 3
Support meter and item randomness barely matter
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Digimon Rumble Arena 2
Character matchups and stage knowledge add light depth
Naruto Shippuden: Ultimate Ninja Storm 3
Team composition and awakening knowledge add a thin layer
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.