Waverider is, in a word, bipolar. While outside of combat he's a friendly enough guy, in combat he is a raging berserker, with Ursus having once said that he looked like 'Zero during the Insurrection on the battlefield.' His ferocity comes from his dedication to the Maximal cause. He simply does not know any other way to show his support than by beating the Predacons. He is best friends with Groundbreaker, and the two were roommates before the expedition. The only person he doesn't get along with is Steeljaw, and that's because of the whole 'cat+water' deal. That and that Steeljaw can't swim.
Waverider was tragically killed in the battle against Unicron, perishing before the Chaos God's optic blasts.
But this was not the end of Waverider.
His corpse was interred in the ancient Autobot Crypt, and the Predacon scientist Requiem needed cyber-cells from a dead body. He found Waverider and brought him back as a Predacon named Tsunami. With no memories past his death, Waverider actually believed Requiem. This changed when he found out about the Predacon's...ancestry. He changed his activation code and name(conveniently into his old one), and escaped. He became a sailor, and was known for sailing any sea on Cybertron with almost supernatural ease. It was here that he met Groundbreaker after his boat sank and Waverider saved him. The two became roommates and best friends.
Waverider is armed with a toxic gas gun, which has a short range but potent effect, depending on the gas he chooses to expel. He can put an opponent to sleep, lock up their joints, and even make them overheat, depending on whatever gas he chooses. He is armed with another gun that fires energy spears, able to pierce almost any armor. These are especially effective underwater, where he is most of the time. For melee combat he carries a thermal cutlass, which heats up to an incredible temperature, able to slice through most metals like butter. Underwater, he is graceful and near unmatched, but on land, his beast mode is literally a fish out of water, and his robot mode isn't too special either.
Waverider has black robot parts, and light gray 'flesh'. His manta mode is dark gray on top and white underneath.
Behind the scenes
Waverider shares a body design with BW Manta Ray, a female transformer(though her toy doesn't look it). His friend Groundbreaker also shares a body design with a fast-food exclusive BW character.