How to show the rows with more data in PowerQuery/PowerBI?

This is more steps. I would personally try to push this logic back to the source but it can be done in power query.

To make this work in power query I had to create another copy  of the table and join the original table to the copy.  I also had to make a key with a merge on Owner, State, and, Color in both the copy and the original  I used that to join in the merge step.  Then I pulled the toy from the joined table.

you can use group by command to solve this.

use the next formula

let
Source = Excel.CurrentWorkbook(){[Name="Table3"]}[Content],
#"Changed Type" = Table.TransformColumnTypes(Source,{{"Color", type text}, {"State", type text}, {"Owner", type text}}),
#"Grouped Rows" = Table.Group(#"Changed Type", {"Color", "State"}, {{"Count", each Text.Combine(List.Distinct(([Owner])))}})
in
#"Grouped Rows"



result in 

Hi heriberto_mb, check this:

Result

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WcsopTVXSUfL1BBLJiUVAUilWB1W4pCgxMw9IB+fl5xdUgqUjU3Ny8suBYo5RQCIpMScHSDlnJBblZKZiUVCZX5kPMzkoNQWk1h9IpOSD9eEUjgUA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Color = _t, State = _t, Toy = _t, Owner = _t]),
    ReplacedValue = Table.ReplaceValue(Source,"",null,Replacer.ReplaceValue,{"Owner"}),
    GroupedRows = Table.Group(ReplacedValue, {"Color", "State"}, {{"All", each if List.Count(List.Select([Owner], (x)=> x = null)) = List.Count([Owner]) then Table.FirstN(_, 1) else Table.FirstN(Table.SelectRows(_, (x)=> x[Owner] <> null), 1), type table}}),
    CombinedAll = Table.Combine(GroupedRows[All])
in
    CombinedAll