Draws "Time Wizard" and subsequently Normal Summons it in Attack Position (500 ATK / 400 DEF). Joey then immediately activates his "Time Wizard's" special ability. Joey's luck roll is successful, so he can transform "Baby Dragon" into "Thousand Dragon" (2400 ATK / 2000 DEF). (NOTE: in the real game, "Time Wizard's" special ability is slightly different and actually uses "Baby Dragon" to gives rise to "Thousand Dragon" through Fusion Summon)(NOTE: If Battle City rules were to permit a Fusion Monstor to attack the turn it was summoned, Joey would have been able to attack directly and won, as Seto only had 700 Life Points remaining).
In the Japanese version, the "Thunder Dragon" Seto discarded had the Kanji for LIGHT in its Attribute, but the two others he added to its hand did not.