conditional group by

In power query, select the ID column and then unpivot other columns. 

Filter the value on <> 0 

or if you are looking for something more like this:

You can use this code:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45W8nRR0lFyBGInIHZWitWJVjIEsgyA2AhMg0RALEMohogYQ9VA1IFETODyIDo2FgA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [Column1 = _t, Column2 = _t, Column3 = _t, Column4 = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Column1", type text}, {"Column2", type text}, {"Column3", type text}, {"Column4", type text}}),
    #"Promoted Headers" = Table.PromoteHeaders(#"Changed Type", [PromoteAllScalars=true]),
    #"Changed Type1" = Table.TransformColumnTypes(#"Promoted Headers",{{"ID", Int64.Type}, {"A", Int64.Type}, {"B", Int64.Type}, {"C", Int64.Type}}),
    #"Unpivoted Other Columns" = Table.UnpivotOtherColumns(#"Changed Type1", {"ID"}, "Attribute", "Value"),
    #"Filtered Rows" = Table.SelectRows(#"Unpivoted Other Columns", each ([Value] <> 0)),
    #"Grouped Rows" = Table.Group(#"Filtered Rows", {"ID"}, {{"Count", each _, type table}}),
    #"Added Custom" = Table.AddColumn(#"Grouped Rows", "Custom", each Table.SelectRows
( [Count],  each [Value] >0 )),
    #"Added Custom1" = Table.AddColumn(#"Added Custom", "Custom.1", each Table.SelectColumns(
[Custom],
{"Attribute"}
)),
    #"Added Custom2" = Table.AddColumn(#"Added Custom1", "Custom.2", each Table.ToList( [Custom.1] )),
    #"Removed Other Columns" = Table.SelectColumns(#"Added Custom2",{"Count", "Custom.2"}),
    #"Added Custom3" = Table.AddColumn(#"Removed Other Columns", "Factor ID", each List.Accumulate(
[Custom.2],
"",
(state,current) => state & current), type text),
    #"Removed Columns" = Table.RemoveColumns(#"Added Custom3",{"Custom.2"}),
    #"Expanded Count" = Table.ExpandTableColumn(#"Removed Columns", "Count", {"ID", "Attribute", "Value"}, {"ID", "Attribute", "Value"}),
    #"Changed Type2" = Table.TransformColumnTypes(#"Expanded Count",{{"ID", Int64.Type}, {"Attribute", type text}})
in
    #"Changed Type2"