What is the best way to make clouds with png images?

I’m currently working on a mobile game. I’m trying to make a simple background with 2D clouds moving up on the background as if it’s a sky. I want to have 2D clouds with different blur effects on each one but I’m unsure on how to import an image and have it as an object in a scene. Would it be best to have multiple different objects for clouds or one overlay where the images are attached to it.

Many people make clouds by stamping a bunch of white circles in a group. You could then use a defusing brush to soften the edges.
Make an Empty GameObject and attach an Image component to it. This will let you animate it it you want.
also check out Recorded Video Session: Making A Flappy Bird Style Game - Unity Learn
Have fun.