head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is reads, and it is a single point.

Reads · Competitive PvP
The 2011 reboot that returned Mortal Kombat to brutal 2D fighting fundamentals.

Execution · Competitive PvP
The Wii U Smash that restored competitive pace and a huge roster of labbable kill confirms.
Mortal Kombat leans Reads (Competitive PvP); Super Smash Bros. for Wii U leans Execution (Competitive PvP).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Mortal Kombat
Combo execution and punish timing
Super Smash Bros. for Wii U
Perfect pivots and precise aerial spacing reward sharp hands.
Mortal Kombat leans a little harder on reads, though the gap is small.
Mortal Kombat
Human opponents adapt; conditioning and counter-guessing rule
Super Smash Bros. for Wii U
Ledge-trap and landing-trap guessing against humans never converges.
Super Smash Bros. for Wii U leans a little harder on variance, though the gap is small.
Mortal Kombat
Near-deterministic systems
Super Smash Bros. for Wii U
Tripping removed; only minor move RNG remains.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Mortal Kombat
Frame data and matchup study converge to known answers
Super Smash Bros. for Wii U
Rage mechanics and kill-confirm percents are deeply labbable.
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.