Classic Aquaman
Successfully complete the game under the easy difficulty setting as Aquaman. Classic Aquaman has no Morphing Claw, which means some of his combo moves are not available. However, he swims slightly faster and his telepathy call is different.
Tempest and Black Manta
Successfully complete the game under the easy difficulty setting as Classic Aquaman. Tempast (Aqualad) has less combos than either Aquaman or Classic Aquaman, and no telepathy. However, he has an Ice Beam combo move. Black Manta also has no telepathy power, but has the best combos in the game (some of which require practice). The easiest move to use is the Heat Ray Beam attack or the Grab Heat Ray attack.