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 Wii entry whose slower pace and infamous random tripping pushed Smash toward defensive mind games.

Execution · Competitive PvP
AKI-engine N64 wrestler that perfected the grapple system later refined in No Mercy.
Super Smash Bros. Brawl leans Reads (Competitive PvP); WCW/nWo Revenge 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.
Super Smash Bros. Brawl
Slower engine lowers the ceiling but spacing still needs hands.
WCW/nWo Revenge
AKI grapple timing and reversal windows
Super Smash Bros. Brawl leans a little harder on reads, though the gap is small.
Super Smash Bros. Brawl
Defensive bait-and-punish yomi dominates its floaty neutral.
WCW/nWo Revenge
Human opponents turn reversals into prediction duels
Super Smash Bros. Brawl leans a little harder on variance, though the gap is small.
Super Smash Bros. Brawl
Random tripping injects genuine uncontrollable RNG into movement.
WCW/nWo Revenge
Slight randomness in momentum swings
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Super Smash Bros. Brawl
Matchup knowledge and ledge play reward study within a campy meta.
WCW/nWo Revenge
Learning rosters' move sets and spirit flow converges
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.