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

Execution · Competitive PvP
Fast arena-fighter execution plus guessing games against a human opponent.

Execution · Competitive PvP
Tests quick ball control and outguessing a human defender's tackles.
Dragon Ball Z: Budokai Tenkaichi 3 leans Execution (Competitive PvP); International Superstar Soccer Deluxe leans Execution (Competitive PvP).
Dragon Ball Z: Budokai Tenkaichi 3 leans a little harder on execution, though the gap is small.
Dragon Ball Z: Budokai Tenkaichi 3
Combo timing, dashes and beam clashes demand fast hands
International Superstar Soccer Deluxe
Pass and shot timing under pressure decide matches
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Dragon Ball Z: Budokai Tenkaichi 3
Versus humans, baiting counters and vanish wars is prediction
International Superstar Soccer Deluxe
Versus a human, faking runs and reading tackles is central
International Superstar Soccer Deluxe leans a little harder on variance, though the gap is small.
Dragon Ball Z: Budokai Tenkaichi 3
Almost nothing hidden once both rosters are known
International Superstar Soccer Deluxe
Deflections and keeper bounces add light chaos
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Dragon Ball Z: Budokai Tenkaichi 3
Character tiers and combo routes form a learnable layer
International Superstar Soccer Deluxe
Formations and set-piece routines are learnable systems
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.
full breakdown
Dragon Ball Z: Budokai Tenkaichi 3 →
full breakdown
International Superstar Soccer Deluxe →