Japanese does not have plurals in the same way that English does. It does have an optional pluralizing suffix. However, the fact that it was not used with "base" does not imply that "base" is singular.
Looking at the sentence structure, it seems to me that "base" was really intended to be singular (which also fits with the context provided by the script on your wikipedia link). Roughly the sentence is structured as follows:
By means of the Federation Army's corporation,
as for yall's base,
entirely CATS has taken
The word I translated into "entirely" could also be translated into "all". However, gramaticly, it still does not modify "base", so I can see no sense in which "all your bases" is a correct, literal translation.
Japanese does not have plurals in the same way that English does. It does have an optional pluralizing suffix. However, the fact that it was not used with "base" does not imply that "base" is singular.
Looking at the sentence structure, it seems to me that "base" was really intended to be singular (which also fits with the context provided by the script on your wikipedia link). Roughly the sentence is structured as follows:
By means of the Federation Army's corporation, as for yall's base, entirely CATS has taken
The word I translated into "entirely" could also be translated into "all". However, gramaticly, it still does not modify "base", so I can see no sense in which "all your bases" is a correct, literal translation.