Voltorb

Shapechanger. Voltorb can use its action to polymorph into a pokeball or back into its true, amorphous form. Its statistics are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.

Adhesive (Object Form Only). Voltorb adheres to anything that touches it. A Medium or smaller creature adhered to the Voltorb is also grappled by it (escape DC12). Ability checks made to escape this grapple have disadvantage.

False Appearance (Object Form Only). While Voltorb remains motionless, it is indistinguishable from an ordinary pokeball.

Static (Amorphous Form Only).  Any creature that touches Voltorb takes 2 (1d4) lightning damage.  If the creature is Tiny, it must succeed on a DC11 Consitution saving throw or be paralyzed.

Pseudopod. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 4 (1d4 + 2) bludgeoning damage.  The target is subjected to Voltorb's Adhesive or Static trait depending on Voltorb's current form. 

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 4 (1d4 + 2) piercing damage plus 2 (1d4) lightning damage.