When the Energy Monster is low on energy, her size shrinks to a minuscule electric creature that is easier to contain than its larger, powered-up form. However, the only way of reducing her size is to "short-circuit" her by drenching her in water (or glass dust, as shown in "Oh, Holiday Cheese"), or if continuous electrical attacks drain most of her energy. It has also been shown that the Energy Monster is not only drawn to large sources of power (such as electronics stores or generators), but is also attracted to shiny things (such as Violet's shimmering hat or the disco ball in "Becky and the Bard").
In the two-part episode "Dinner or Consequences", Doctor Two-Brains made a helmet to harness the Energy Monster's power for his cheese ray. But when the Energy Monster put on the helmet, she started talking. It is at this point that the Energy Monster revealed that she is a girl and that her preferred name is Maria. In fact, she started talking about everything, savoring every bit of her ability.
When the helmet was confiscated later by WordGirl, the Energy Monster was disappointed, and yearned to find her voice helmet again. She followed the doctor as he traced the helmet to the Botsford home, and acquired it again to recover her abilities. Before she and WordGirl could battle again, however, Two-Brains became fed up with her over-talkativeness and sprayed Maria with water from a nearby hose, shrinking her and damaging the helmet so she couldn't talk again.
While able to talk, she told WordGirl she was stronger than all the other villains she faced. Maria is the only villain who has lost the ability to communicate words as a result of WordGirl's actions. She has not been given back the ability to talk since then, which might qualify as a cruel and unusual punishment. Although it was Two-Brains who did this, no attempts have been made to restore her ability to speak, and Becky did not seem concerned about helping her, casually depriving her of the helmet initially, and rushing home to try and get out of her mega-grounding instead of staying at the prison with the monster.