The FinalManda's name comes from Godzilla: Final Wars's title, specifically the word final (ファイナル?, Fainaru), and Manda, which comes from Manda's Japanese name, Manda (マンダ?).
Detail
FinalManda's feature is combined by multiple Chinese and Japanese dragons, it is also combined with the face similar to the ShodaiManda design. Manda's neck is a lot thicker and which manifest in the appearance of fans around its neck forming a hood, as seen in most species of cobra. Its body length is twice as long than his body was in the Showa series, and instead of having feathers, the FinalManda design has spikes growing out of its back and arms, with the extent of having a beard growing from its chin and having barbs growing from the sides of its body.
The FinalManda design looks similar to Shenron, the wish granting dragon from the Dragon Ball series. However, since both are based on Eastern Dragons, it is unlikely that this is anything more than coincidence.