Most nouns ending in -o add -es to form the plural (with some exceptions like photo/photos).
Retro is regular. It follows the -es Addition rule.
Use plural verbs: "The retroes are ready" (not "is ready").
Yes. The plural retroes is standard across all English variants.
The word retro follows the standard English pluralization rule. When forming the plural, retro becomes retroes. This follows the -es Addition pattern, which is one of the most common plural rules in English.
Understanding why retro becomes retroes helps with spelling and pronunciation. Most nouns ending in -o add -es to form the plural (with some exceptions like photo/photos).
When using retroes in writing, remember that it functions as a plural noun in sentences. It pairs with plural verbs and pronouns. For example: "The retroes are ready" (not "is ready"). This subject-verb agreement is essential for grammatical correctness.