They first appeared in Super Mario World VR. They, along with Icicle Koopa's and Redhot Goomba's are the new enemies. They seem to think that Mario is invading Star World and they are trying to defend it.
Electro Guy also appear in Yoshi's Isle U as rare enemys living on Yosher's Isle. They mainly appear in the Funky Forest and Crystal Caverns areas. To attack, they charge up with their Thunderbolts and then charge extra fast as Yoshi. If he is hit, he will be paralyzed for a short time, and while he is recovering the Electro Guy(s) will return to their area.