The study compared the tactical behaviour and skill efficacy of young novice basketball players during small-sided games (SSGs) in situations of numerical equality (3vs.3), numerical superiority (3vs.2), and a non-scorer floater (3vs.3 + 1). A total of forty-five schoolchildren (11.55 ± 0.49 years) from both sexes with no previous experience in basketball participated in ten four-minute SSGs of each format for four 1-h sessions. The Game Performance Assessment Instrument was used to analyse tactical behaviour and skill efficacy. Friedman’s test, Dunn’s post hoc test, and r effect size were used to compare the variables between SSGs. Pass inefficacy (3vs.3 > 3vs.2; p = 0.004; large effect), rebound efficacy (3vs.2 > 3vs.3 + 1 and 3vs.3; p = 0.002; large effect), support (3vs.3 > 3vs.3 + 1 e 3vs.2; p = 0.002; medium effect), and guard/mark (3vs.2 > 3vs.3 and 3vs.3 + 1; p = 0.001; medium effect) showed significant differences between SSGs. The results support the hypothesis that an unbalanced SSG is less complex than an SSG with numerical equality, as the technical-tactical performance is higher in unbalanced SSGs.