Slitheroot = Gobohebi = Gobou (Burdock root) + Hebi (snake)

Waturtlemelon = Suikame = Suika (watermelon) + Kame (turtle)

An additional name in this ep is Gobou, the king of the Straight Group. This is another pun: Gobou (Burdock root) + Ou (king)