Taking into account the different Attack and Special Attack stats you have listed, Dark Pulse will be doing a little more damage than Bite, despite the lower Special Attack. With that being said, it not that much stronger, only beating it by a little bit.
Here is a quick calculation to show you the difference. I manually changed Crobat's stats to match what you gave above, but the Glalie is level 50. I am using Glalie because its Defence and Special Defence are the same, eliminating that from affecting the outcome.
0 Atk Crobat Bite vs. 0 HP / 0 Def Glalie: 38-45 (24.5 - 29%) -- 99.6% chance to 4HKO
0 SpA Crobat Dark Pulse vs. 0 HP / 0 SpD Glalie: 43-51 (27.7 - 32.9%) -- guaranteed 4HKO
So, as you can see Dark Pulse does a little bit more damage.