If I beat the eleite four ahd champion, cause ik u can only load by pressing F4, can I continue the game and battle the other gym leaders or is it done and overwith?

When you load the save state it is from the last place you "saved state" Or in other words the last time you pressed F2. It does not load whatever save you might have made in the actual game's menu.

I hope that sheds some light on your issue.

Just to sort of rephrase Jordanv78's comment.

F2 is the emulator's save. It is not the actual game's save. Whenn you press F4 you load the save state from the emulator. This is not at all connected to the save you do from the game menu.

When you beat the Elite 4, it will go back through the opening scene and probably find that there is no save file (because the game doesn't have one). Some games can save in the game, but you need the emulator save to actually come back to it. If you can save through the menu (in the game) successfully, then this means you will be able to continue after the Elite 4. Just remember that you still need to press F2 for the emulator save.

The real problem here is the separation of the game's save (through the menu) and the emulator's save (F2). The emulator save is the one you need if you want to actually save it and come back to it. The in-game save (through the menu) is only really useful for after the Elite 4. Some games do it, while others don't.

I know this was longer, but I thought it would make more sense if I gave more details.