head to head
Neither is simply harder - they are hard in different places. Divekick demands more reads; Super Smash Bros. Brawl demands more execution.

Reads · Pure Mind Games
A two-button parody fighter that strips fighting games down to pure one-hit-kill spacing reads.

Reads · Competitive PvP
The Wii entry whose slower pace and infamous random tripping pushed Smash toward defensive mind games.
Divekick leans Reads (Pure Mind Games); Super Smash Bros. Brawl leans Reads (Competitive PvP).
Super Smash Bros. Brawl leans clearly harder on execution.
Divekick
Two buttons, one-hit kills; almost no physical ceiling.
Super Smash Bros. Brawl
Slower engine lowers the ceiling but spacing still needs hands.
Divekick leans clearly harder on reads.
Divekick
Pure spacing yomi against an adapting human is the entire game.
Super Smash Bros. Brawl
Defensive bait-and-punish yomi dominates its floaty neutral.
Super Smash Bros. Brawl leans clearly harder on variance.
Divekick
Fully deterministic.
Super Smash Bros. Brawl
Random tripping injects genuine uncontrollable RNG into movement.
Super Smash Bros. Brawl leans a little harder on optimization, though the gap is small.
Divekick
Character angles and gem choices are quickly mapped.
Super Smash Bros. Brawl
Matchup knowledge and ledge play reward study within a campy meta.
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.