It works on the teensy 3.6 without Pullup-Resistors. Perhaps they are inside the OLED-Baords.
I use 2 cheap OLED-Boards with 4 Pins each, GND, VCC, SCL and SCA.
Both use the same I2C-Address but they use different I2C-Ports.
I thought that it is much more complex, but finally it was very easy...