Technically it does not, but in a sense that you are less likely to be hit, it kind of does. It doesn't because you can use double team 6 times to max out your evasion, but you could still use sand attack 6 times to lower your foes accuracy all the way, meaning that double team doesn't affect your opponent's accuracy, but it still makes them less likely to hit you.
-6-25%
-5-29%
-4-33%
-3-40%
-2-50%
-1-66%
0-100%
+1-150%
+2-200%
+3-250%
+4-300%
+5-350%
+6-400%
Whenever you use a move like howl that raises it one stage, and when moves say harshly fell or sharply rose, then that means 2 stages up or down.