What is a group of Attire called?

A group of attire is commonly called a Suit. Other collective nouns you may see include Ostentation.

Collective nouns for attire refer to groups or collections of clothing or outfit-related items. Often used to designate a particular set of clothing or associated pieces, collective nouns for attire aid in organizing and categorizing various garments or accessories. These nouns highlight the shared features or functions of a group of garments worn by individuals in specific contexts or for particular occasions. Examples of collective nouns for attire include "wardrobe," which encompasses a collection of clothing items found in one's closet or overall inventory. "Outfit" may refer to a set of coordinated garments worn together to achieve a specific look or convey a particular style. "Attire" itself can signify a general assemblage of clothing, indicating the collective garments worn in a specific situation or during certain events. Other collective nouns for attire can further differentiate specific categories, such as "attire ensembles" denoting coordinated clothing sets or "costumes" representing a collection of outfits used in theatrical or festive performances. "Uniforms" depict attire conforming to a particular profession, organization, or team, displaying unity and identification among members. Collective nouns for attire assist in communicating and categorizing various aspects of clothing. They enable efficient communication while organizing outfits, choosing the right garments for specific situations, or evaluating fashion trends, contributing to a broader understanding of clothing as a cultural and practical element of society.