show_y_guides=False turns off the dashed horizontal guide lines, but also removes the solid horizontal axis at y=0.
On the other hand, show_x_guides=False still keeps the the vertical axis at x=0.
So this code:
xy_chart = pygal.XY(show_y_guides=False, show_x_guides=False)
xy_chart.add('A', [(-3, -4), (-1, -2), (1, 2), (3, 4)])
xy_chart.render_to_file('xy.svg')
results in a graph with a vertical line at x=0 but no horizontal line at y=0.
I think there should be a way to separately turn on/off the axis at zero, independently of the guides.