Is there any way to take bg tiles and transfer them to a sprite sheet?

Erm, the BG sheet is a GRP, so it can already be used as a spritesheet. If you want to use a BG MAP, then I don't know how to help you.

What I'm asking is, is there an easy way to take some of the built in sprites on the bg sheet (grp5) and paste them on a sprite sheet (grp4)

They removed the copy across page function from the PAINT tool in an earlier update. Sorry, I don't know what to do.

If you write "SPPAGE X", you can use Xth grp sheet as sprite sheet. And if you write "BGPAGE X", you can use Xth grp sheet as BG sheet.

Thanks ,@Hanzo, but I still want to use a normal sprite sheet as well, instead of placing GRP5 instead of GRP4. Thanks anyways

He wants to copy some tiles from the bg grp to the sprite grp.

Yes, without using the GCOPY command and finding the exact coordinates of each sprite, the only thing you can do is load the sheet to a seperate layer. Since all character sheets and other graphical sheets are stored as general GRP files, all you need to do is specify a different page when loading.