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

Execution · Competitive PvP
Tests shot timing and faking out human defenders amid item-driven chaos.

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 Strikers Charged leans Execution (Competitive PvP); Super Smash Bros. Melee leans Execution (Competitive PvP).
Super Smash Bros. Melee leans clearly harder on execution.
Mario Strikers Charged
Timing tackles, charged shots and goalie deflections needs quick hands
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 Strikers Charged
Versus humans, faking shots and baiting tackles drives goals
Super Smash Bros. Melee
Reading DI choices and opponent adaptive habits is constant and non-convergent
Mario Strikers Charged leans clearly harder on variance.
Mario Strikers Charged
Items and stage hazards inject swingy chaos into matches
Super Smash Bros. Melee
Stage hazard RNG and spawn positions add marginal chaos
Super Smash Bros. Melee leans clearly harder on optimization.
Mario Strikers Charged
Captain abilities and team builds reward knowing the systems
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.