I know it says " The One Character That Would've Made Brawl Perfect", but a character from any one of these series' would've made me happy.
1. Megaman(Megaman X) - Megaman/Megaman X/Protoman
2. Chrono Trigger - Frog/Chrono/Magus
3. Starcraft - Jim Raynor/Sarah Kerrigan/The Queen of Blades
4. Final Fantasy - Cecil(V)/Sabin(VI)/Terra(VI)/Shadow(VI)/Cyan(VI)/Cloud(VII)/Cid(VII)/Rikku(X) The list goes on...
5. Kingdom Hearts - Sora/Riku