The ornamental design for a ballholder, as shown and described.
FIG. 1 is a perspective view of the ball holder showing my new design, the inflating needles shown in broken lines being for illustrative purposes only, and forming no part of the claimed design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left view thereof;
FIG. 5 is a right view thereof;
FIG. 6 is a top view thereof, the inflating needles shown in broken lines being for illustrative purposes only, and forming no part of the claimed design;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is a perspective view showing the design in association with a ball, the ball and inflating needles shown in broken lines being for illustrative purposes only, and forming no part of the claimed design.