Compare one value to multiple columns values

Apologies, could you clarify the requirement as I may have misunderstood something. 😅

I'm not sure what you mean by "compares Column A to Columns B, C, D ... and not the specific text within those columns."

My original understanding of the requirement was:

Within each row, if the value in column A is equal to at least one of the values in columns B, C, D, E, F, then add a column containing "MATCH" otherwise add a column containing "MISMATCH".

EDIT: Did you mean that, aside from column A, there are an arbitrary number of additional columns which you want to reference without specifying their names? If so, I would still use List.Contains along with Record functions as follows:

let
  Source = #table(
    type table [A = text, B = text, C = text, D = text, E = text, F = text],
    {
      {"MC/001", "MC/001", "MC/002", "MC/003", "MC/004", "MC/005"},
      {"MC/002", "BD/001", "BD/002", "BD/003", null, null},
      {"MC/003", "BD/001", "BD/002", "BD/003", "MC/001", "MC/003"},
      {"MC/004", "BD/001", "BD/002", "BD/003", "MC/001", "MC/002"}
    }
  ),
  ReferenceColumn = "A",
  #"Added Match" = Table.AddColumn(
    Source,
    "MATCH",
    each
      if List.Contains(Record.FieldValues(Record.RemoveFields(_, {ReferenceColumn})), Record.Field(_, ReferenceColumn)) then
        "MATCH"
      else
        "MISMATCH",
    type text
  )
in
  #"Added Match"