Hello,
Thank you for the useful questions 
It is known that the more dark pixels there are, the lower the battery consumption depending on the characteristics of OLED displays generally equipped by the recent watch devices.
The results of the watchface app created by WFS are optimized so that the screen is not updated unnecessarily. Therefore, more static watch faces consume less battery than dynamic ones.
Since the accelerometer sensor is one of the most widely used sensors in watches, it cannot be considered to be turned on according to the use of the watch face and in itself does not seem to have a significant impact on battery use. However, using accelerometers such as gyro effects can lead to frequent screen updates and high battery consumption.
Of course, it is recommended to use media images of exactly the same size as those placed on the screen. For example, since the screen size of WFS is 450x450, it is best to use an image of 450x450 size for a background image that fills the screen.
In WearOS, complication is data provided by another application to the watch face, so using a lot of complication slots means that other application services operate more in the background, so it can be seen that the battery is used more. However, this is not always right because the update cycle or operating environment varies depending on the type of application, and complication system is optimized at the platform level.
In this case, it is difficult to predict any difference.
It is recommended to remove them before build your app.
Here is the information you can refer to when making watchface.
Looking forward to your wonderful watchface! 