I'm trying to control 4 vibration cells Individually which rate at 2-3.6V. After some research I see it's safer to use a transistor so the motor isn't on the IC's pin directly and also to have diodes too as the motor can do weird stuff to the current or something, anyway..
I'm not an ATTiny expert, so I won't comment on that aspect of your circuit, but you should put resistors between your IO pins and the transistor bases (1k should work) to limit the control current to them.
Also, google flyback diodes to see how to connect them up ('backwards' across your motor).
You use the transistors as emitter-followers. That's fine if you add the flyback diodes, but the voltage over the motors will be 0.6V lower. The diode in the circuit will cause another voltage drop of 0.6V. So the vibration cells will get only 1.8 Volt.
Interestingly though the adafruit link says its safe enough to use them directly on an Arduino pin with a 100 ohm resister. Do you think thats safe with an attiny too? It would save a lot of components!
Your circuit is okay.
You could add a small 100nF over the ATtiny85 to decouple the 3V battery.
The ATtiny85 can only deliver 20mA (I think so, but I'm not sure). So for the ATtiny85 you would need a higher value. Using a resistor with 100 ohm will also lower the voltage over the motor.