Add nothing to USJ
If the children do USJ, that day stays at Universal City. The JR exit is the gate. Express passes follow that day's notice. Eat at CityWalk and return to the hotel. Do not push on to Kaiyukan.
A half-day if you are not at Universal City
Kids Plaza in Tenma is about 5 minutes from Ogimachi Station; closing follows that day's notice. Tennoji Zoo is the Dobutsuen-mae exit. Kaiyukan is a port half-day. Pick one of the three.
Pushchairs and stairs
Umeda and Namba have many exits — read the lift signs before you leave the gate. Gokuraku Bridge and the Kiyomizu slope are poor with a pushchair. Kuromon is wet underfoot; go in the morning and leave by afternoon.