head to head
Neither is simply harder - they are hard in different places. Mario Sports Mix demands more variance; Super Smash Bros. Melee demands more execution.

Execution · Competitive PvP
Party sports where light timing and item luck outweigh deep strategy.

Execution · Competitive PvP
A platform fighter with one of the highest execution ceilings in any competitive game, layered on top of deep human reads.
Mario Sports Mix leans Execution (Competitive PvP); Super Smash Bros. Melee leans Execution (Competitive PvP).
Super Smash Bros. Melee leans clearly harder on execution.
Mario Sports Mix
Timing shots and blocks matters but stays party-game forgiving
Super Smash Bros. Melee
Wavedashing, L-cancels, and tech-chasing set an extreme physical ceiling
Super Smash Bros. Melee leans clearly harder on reads.
Mario Sports Mix
Human opponents fake passes and shots in versus play
Super Smash Bros. Melee
Reading DI choices and opponent adaptive habits is constant and non-convergent
Mario Sports Mix leans clearly harder on variance.
Mario Sports Mix
Item drops and special shots inject deliberate chaos
Super Smash Bros. Melee
Stage hazard RNG and spawn positions add marginal chaos
Super Smash Bros. Melee leans clearly harder on optimization.
Mario Sports Mix
Shallow team and court knowledge caps quickly
Super Smash Bros. Melee
Character matchup tiers and optimal movement routing are deeply studied
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.