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
Arcade tennis with timing-based PvP mind games.
Digimon Rumble Arena 2 leans Execution (Competitive PvP); Mario Tennis Aces leans Execution (Competitive PvP).
Mario Tennis Aces leans a little harder on execution, though the gap is small.
Digimon Rumble Arena 2
Smash-style movement and attack timing in chaotic arenas
Mario Tennis Aces
Shot timing, charge mechanics, footwork
Mario Tennis Aces leans a little harder on reads, though the gap is small.
Digimon Rumble Arena 2
Couch opponents bait digivolutions and punishes
Mario Tennis Aces
Online tennis demands reading opponent placement
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
Mario Tennis Aces
Mostly deterministic ball physics
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
Mario Tennis Aces
Character matchups and tech routes
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.