The phrase "most buddy-buddy" is an informal term used to describe a close relationship between two individuals. Synonyms for the phrase could include "chummy," "close," "intimate," "familiar," "amiable," "affectionate," "cordial," "friendly," "companionable," "sociable," "pally," "bosom," "dear," "best," "near," "warm," and "attached." These words all suggest a strong bond between two people, whether it be a mutual affection or a shared interest. Using these synonyms in place of "most buddy-buddy" can add variety and depth to your writing, making it more engaging and expressive.