Grinnades are walking bombs first seen in Skylanders: Trap Team that attempt to explode on the Skylanders. One Grinnade is a trappable villain.
In Skylanders: SuperChargers and Skylanders: Imaginators, they had their attack patterns slightly changed, first winding up for a jump then exploding when they touch the ground again. A common trap in both games is also a box full of Grinnades, that have no health and immediately try to explode as attacks remove them from its contents.