You can cast Voracious Greatshark without a target for its enters-the-battlefield triggered ability. That ability will simply not happen. It won’t cause Voracious Greatshark to counter itself. It’s not that hungry.
Legalitet:
Standard: Ej legal
Pioneer: Legal
Modern: Legal
Legacy: Legal
Vintage: Legal
EDH / Commander: Legal
Pauper: Ej legal
Explorer: Legal
Historic: Legal
Brawl: Ej legal
Premodern: Ej legal
93/94: Ej legal