Moving Drupal database from MySQL to Oracle
This may be another long shot and I certainly haven't tried it myself, but assuming that the Features module works on a fresh install on top of Oracle, you may be able use it to export your content types, menus, and views from the MySQL-based site. The Features extra module might allow you to export the taxonomy too.

You could then add the Services module on the MySQL site to serve up content to either the Feeds module or maybe the Web service client module on the Oracle-based site.

Another caveat is that I don't know how well either of these steps would handle the i18n.

Good luck!