I am back, and ready for more fun!
Here comes the first one, let's get this done!

Rocks are my foe, but don't laugh for long
I'll take out my foes with my deadly songs

My name is long, but my size is small
And when I grow, I'll make trainers bawl

Fairies can't touch me, not well at least
And with the right moves, I slay the beast

Who am I?