You can just calculate the angle between your ball and the paddle and use this for the direction of bouncing.

Maybe I do something really silly but this function will work for calculating the angle:

#returns angle and distance between two points
def angle_distance(x1,y1,x2,y2):
   distance = ((x1 - x2)**2 + (y1 - y2)**2)**0.5*pos_neg(y1 - y2)
   try:
      angle = math.acos((x1 - x2)/distance)/math.pi*180 + 180*(y1 - y2 >= 0)
   except ZeroDivisionError:
      angle = 0
   return angle,abs(distance)

#returns -1 or 1 if value is negative or positive
def pos_neg(value):
   return ((value >= 0)*2-1)

I hope this will help. If you want some more kollision stuff, also for rotated rectangles, just ask.

I think pygame doesn't have complex functions to get collisions. But now to your question:

You can just calculate the angle between your ball and the paddle and use this for the direction of bouncing.

Maybe I do something really silly but this function will work for calculating the angle:

#returns angle and distance between two points
def angle_distance(x1,y1,x2,y2):
   distance = ((x1 - x2)**2 + (y1 - y2)**2)**0.5*pos_neg(y1 - y2)
   try:
      angle = math.acos((x1 - x2)/distance)/math.pi*180 + 180*(y1 - y2 >= 0)
   except ZeroDivisionError:
      angle = 0
   return angle,abs(distance)

#returns -1 or 1 if value is negative or positive
def pos_neg(value):
   return ((value >= 0)*2-1)

I hope this will help. If you want some more kollision stuff, also for rotated rectangles, just ask.