Audio samples for the most part. One example is my band covers Bruno Mars' "Locked Out of Heaven". We play the "yeah-eh-eh-eh" sample that occurs after each line in the verses, the clap sample, plus the rising pitched "woop woop woop" playing under the "you make me feel like I'm locked out of heaven". We have other songs that have multiple samples interspersed throughout the song, making it hard to hit the play button for audio samples while playing keys parts. Another example would be the "doh" sample in "Uptown Funk" mapped to multiple keys for pitch control.
Our previous keyboardist had more powerful gear that handled all this. Our new guy has the XW-P1 plus a Casio Privia, and we're trying to figure out whether his gear can somehow handle it, or will we have to purchase a separate piece of gear to perform this task.