Well, thank you for your help. But it didn't work.
Ok, I'll explain it again. Outside Godot, the picture contains both Pikachu and that block (Pikachu standing on top of it). But in Godot, the picture appears to only have the block, the Pikachu sub-image cannot be seen. I don't know why this is happening. Now, I am currently using both sub-images as separate images. This is working. Anyways, thanks for your help.