In a project where there is 4 6V DC motors and other motors and components, all the voltage adds up to 35V, but specifically each individual component needs 6V or less. Can I use a LiPo battery that is about 7.2V (with the correct amps), to power the whole thing ?
Currents are added, not voltage. You need a 6V power supply capable of handling the total stall current for the motors, so please post a link to those motors.
You do not sum the voltages. You can use a single supply and use step down (buck) converters or step up (boost) converters to derive the voltages that you need.
Each component needs the voltage that is specified for it. Also each component needs the voltage supply to provide enough current for that component. To advise you properly we need to know exactly what components that you have and their specifications. The specifications are usually listed in a data sheet. Post links to the data sheets.
Some components have very specific or a narrow range of supply voltage. For instance a mega328 mlcrocontroller like in the Uno or Nano needs a supply 4.5V to 5.5V. Others have a wider range. A stepper motor with a current control stepper driver can have 8V to 45V (depending on the driver).
this is the link with the data sheet to the tt motors.
This is the data sheet for the SG90 servo (just 1 of these):
This is the data sheet for the tt motors (i am using 4 of these):
ultrasonic sensor data sheet:
Can someone recommend a power supply to power all of this?
I think that a 5-6V, 4 Ampere (minimum, more current is better) power supply would work for four of the pictured motors and the SG-90 servo.
To be safe in all situations the power supply should be able to handle the total stall current for all the motors at once, 6 Amperes according to the Adafruit web page, plus 1 Ampere for the servo. But in practice you can usually get away with somewhat less.
4xAA batteries, if fresh, will run the setup for a short while, or use a wall wart.
Probably.
You don't add voltages as they are all connected to the same terminals.
Consider; You have a computer that requires 120VAC, and a phone charger that requires 120VAC. You wouldn't think you need 240VAC to power both. Same with your project.