Is there a way i can record/stream speedruns of pokemon emerald while i play it on my GBA?

The only option directly from GBA is to use a Webcam to record you screen. If you still want to do console speedruns then you can use the GBA Player attachment for the Nintendo Gamecube and use a capture card to obtain footage, or use a Nintendo DS (Phat) with a built in Capture Card and use footage from that. Other than that the third option is emulation, for Pokémon Emerald you can use VBA or VBA-rr