Hey! I am adding a pet update to my game, but I need a hand.
I want to make a shop where you can equip a pet, but I want a image of the pet, with no background, so you can see the pet only.
Similar to this in adopt me,
this is what needs to be the final product for the pets. ( The round thing is where the pet
shop would be) 
Look foward to hearing from you!
Generally the best way to do this is to use a ViewportFrame. Each button has a Viewport frame with the appropriate pet model in it, and it will give you exactly what you want. You can even make them spin as a bonus. A guide on how to use them can be found here:
https://developer.roblox.com/en-us/articles/viewportframe-gui
Edit: Although for some reason it tells you to make it entirely out of code - you can insert and edit viewport guis like any other gui, you just need to be able to set up the camera. Here’s a more to the point guide: ViewportFrame Release
Thanks for the help! I will try this out and write back if I need further assistance.