Localytics partners with the largest mobile-focused ad networks, which constitute more than 85% of the mobile ad market. You'll find a partial list of Localytics ad network partners here.
You can use the "custom source" feature of the Localytics Dashboard to track users acquired from non-integrated acquisition sources here.
Localytics also maintains an Attribution API to enable customers who use third-party attribution services to easily leverage other vendors to track advertising campaigns (and some types of organic user acquisition activity) and see the results in Localytics. Currently, all major mobile-focused attribution companies have built integrations with the Localytics Attribution API.