Simple trophy. Once you complete both acts of a stage, it will be fully restored and the white statue standing next to it will return to normal. Planet Wisp is the final stage of the game with an NPC accompanying it, and once you have completed that just walk through the stages and talk to everyone. I’m not sure if Metal Sonic, Shadow and Silver are required for this trophy, but you will earn a trophy for every one of them defeated, so it doesn’t hurt to try. Aside from that, they give you a Chaos Emerald which will be needed for the last boss.