There are 6 Prestige Badges in total. To unlock all 6 you must play each challenge on Normal and on Hardcore. They do not stack unfortunately. From Normal to Hardcore isn't much of a difference. Just get a good party and start clearing out the challenges one by one.
*You can create a match with just 2 people to start, you can choose up to 4 players.
Note: Must complete all challenges under the given time, and with the exact amount goals to receive the achievement for the given challenge!