You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allredirects garcontinue="Checking_Pokemon_IVs|2687" />
  </query-continue>
  <query>
    <pages>
      <page pageid="305" ns="0" title="Catchable Pokemon" />
      <page pageid="915" ns="0" title="Base experience" />
      <page pageid="2448" ns="0" title="Cerulean Cave B1F" />
      <page pageid="2449" ns="0" title="Cerulean Cave 1F" />
      <page pageid="2570" ns="0" title="Cerulean Cave 2F" />
      <page pageid="3178" ns="0" title="Cascade Badge" />
      <page pageid="3180" ns="0" title="Rainbow Badge" />
      <page pageid="3192" ns="0" title="Rising Badge" />
      <page pageid="4505" ns="0" title="Burnt Tower" />
      <page pageid="5643" ns="0" title="Bug" />
    </pages>
  </query>
</api>