Electricity has no mass and weight indeed, but the Toxtricity kind stores it by secreting mucus inside their body, the more electricity, the more mucus.
Source: Believe me, dude.
Doodled a Kaiju and Megachonk Dingodile
Bramble might have developed a lil addiction, but the dumbass wont stop untill all that electricity make his stomach so swollen that he can't move.