Drill-X is a boss for SSB4. His theme is the same as it has always been. He is fought in Story Mode by Spyro as a 3DS-exclusive boss. He is revived by The Chaos King. Here's the dialogue that indicates the fight.
===It's the end of the track, Spyro! This drill-bot is on the scene! I'll knock you forward and back with a robo attack 'cause you're messing with the wrong machine!===
Hold on, time out, Spyro! There's something up with my drill. But you better watch out, You'll be down for the count When I show you my smashing skills!
Fourth and Final Verse
What did you do, Spyro?! You've just won the final round! I can't keep the beat And I'm feeling defeat, And my systems are all shutting down...
Spyro's corresponding quotes
Before the battle
"Uh.....what the heck?"
After the first verse
"....How do you know my name?"
After the second verse
"This is awkward."
After the third verse
"I never thought I'd see this guy again but, so it happened and, well, here I am."
Before the fourth and final verse
After the fourth and final verse
"Yeah! I did it! Now to meet up with Mario and Rayman."