Out of the the box, the V2 Exadata supported 18.104.22.168. The latest Exadata servers (X2-2 and X2-8) are installed with 22.214.171.124, and 126.96.36.199 once it's supported on Exadata. It's not possible to run 10g using Exadata storage.
Both oracle database versions 188.8.131.52 and 184.108.40.206 are currently supported.
Since September 2011, no new exadata bundle patches for 220.127.116.11 are issued by oracle.
Exadata certification/support for 18.104.22.168 is pending, as andy indicated.