god fucking dammit sakhrgkasgkdasjfgaks
Anyways, the reason it isn't showing up is because you misinterpreted what I said and removed XY entirely. UV vertices and XY vertices are intertwined with each other. UV sets the position on your image as a vertex point on the game field XY distance from the object's actual position. When you have all four vertices up, it will make a rectangle. Say the XYs were set like this:
ObjEffect_SetVertexXY(objlightning,0,-80,-300);
ObjEffect_SetVertexXY(objlightning,1,80,-300);
ObjEffect_SetVertexXY(objlightning,2,80,300);
ObjEffect_SetVertexXY(objlightning,3,-80,300);
Then the lightning will be drawn in a rectangle with the object's actual position being in the direct center.
ObjEffect_SetVertexXY(objlightning,0,0,0);
ObjEffect_SetVertexXY(objlightning,1,160,0);
ObjEffect_SetVertexXY(objlightning,2,160,600);
ObjEffect_SetVertexXY(objlightning,3,0,600);
Then the top-left corner of the lightning is the object's position.
ObjEffect_SetVertexXY(objlightning,0,70,-50);
ObjEffect_SetVertexXY(objlightning,1,160,-110);
ObjEffect_SetVertexXY(objlightning,2,130,370);
ObjEffect_SetVertexXY(objlightning,3,240,0);
This will totally skew the graphic and I have no idea where the object position actually is, but I don't really care.