Need help with a costume for Halloween?

I already have my actual costume. I'm the Queen of the Vampires lol.

This costume's for something else.

In marching band, the day of practice that's closest to halloween is the day when you can wear a costume. And you also have to dress in sections (meaning, flutes have to have the same theme, clarinets have to have the same theme, ect) and I'm a clarinet. We're doing pokemon (it's apart of an inside joke kinda) and I'm being Torterra (another inside joke).

I need ideas of a makeshift costume for Torterra. Something that doesn't require too many supplies. I don't wanna make my section look bad ^^

PS - just in case you were wondering, a couple of the pokemon my section is dressing up as include squirtle, charmander and poliwag. My section leader is being Ash. :-)