The description for Big Ol Hero says
Win a round of dodgeball in which you had been the last man standing.
The ribbon can only obtain n Coop VS, Social or Core mode. That applies for all VS ribbons.
Thanks to ClevelandFan
The easier method is Just get a squad of 5 and play coop versus on casual. Vote for dodgeball and get 4 players killed. The last person kills the remaining bots.
As long as the last one actual kills all remaining bots.
Thanks to Kelle1994
To boost this one you have to use two complete teams (10 players).
You can do it with less people if someone uses a second controller.
(Hint: Minimum are 6 players 2 people with second controllers on each team.)
(Hint: The team leaders should made a list of their team nembers to note how many ribbons each one get.)
To avoid interfering with other players switch the region to Latin America or Asia/Australia.
You find it under option and region.
Note: Both leaders must be in the same region.
Go to Versus and select Core Mode / Dodgeball
The team leaders should push the buttons synchronized to start the search.
This will increase the chances to find each other.
1.) Meet at some point on the map.
2.) The player who will get the ribbon from team 1 steps aside or stays at the spawn point.
3.) Team 2 kills everyone else.
4.) Now the player who will get ribbon from Team 1 kills team 2.
The player get the ribbon.
Change player and team every round.
For a ten player party you have to play 100 rounds. That is nearly 15 matches.
(Hint: After each match the team leaders should secure that everyone push B for quitting the statistic fast, so why can start the search again.)