Soundwave was Megatron's most trusted lieutenant, constantly deployed on reconnaissance missions with his cassette army and integral to pretty much every major Decepticon operation against the Autobots.
Back on Cybertron, he'd use his alt-mode as a roadside fixture to surveil the Autobot city of Iacon, where he picked up crucial intel about their plans to hunt for energy off-world. When Megatron launched his assault on the Autobot ship the Ark, Soundwave was right there—and he went down with everyone else when the vessel crashed on prehistoric Earth, leaving the whole crew locked in stasis.
Once the Transformers came online in 1984, Soundwave became indispensable to the Decepticon operation. He spearheaded energon cube production and helped architect plans for a new space cruiser to get them back home to Cybertron. His mind-reading abilities proved especially useful; he once extracted an antimatter formula straight from Chip Chase's brain. Beyond that, Soundwave and his cassette crew ran constant surveillance ops against the Autobots, making him far more than just backup—he was the backbone of their intelligence network.
Content compiled by AnimeList.moe from publicly available sources.