Pep responds with the leaderboard whenever someone asks for it on a public channel. You can send messages to it like 

@pep leaderboard or @pep rankings

Please send these on the public channels so everyone on the channel can see the leaderboard. Only the top 10 people in the team get entry into the leaderboard. 

If you want to see your rank, points and badges privately you can dm Pep profile.