Gonna post the ones i have done to give you all ideas of what's doable.
yes i think i'm funny
Future Lawyer: Read the Rules.
Appreciative: Read the Credits.
Smogonite: Click the “Forum” link.
Commander: Use a chat command like /dt or !ds.
In The Matrix: Use /help and see many commands at once.
Lucky?: Play a Random Battle or Unrated Random Battle.
New Meta: Play an OU match.
Specialist: Play any match besides Random, Unrated Random, or OU.
The More the Merrier: Play a Doubles match.
Ruiner of Alph: Play a past-generation match.
OMnipotent: Play an Other Metagame or Pet Mod match.
Lucky!: Play a randomized format besides Random Battle or Unrated Random Battle.
Nice to Meet You!: Play Super Staff Bros.
Chaotic: Join the Lobby room.
Everything OK?: Join the Help room.
Polyglot: Join an alternate language room.
Epic Gamer Alert: You joined a gaming or games-focused room.
Finding My Place: You were in 4 rooms at once.
Chameleon: You were in 15 rooms at once! Any more than that, and they won’t be saved between sessions.
I also put together two of my own:Kind Stranger: Host your first giveaway in Wi-Fi
JavaScript:
title: "This is the Way",
desc: "Spoke in a chatroom for the first time!",
JavaScript:
title: "IT'S OVER.. 1500?",
desc: "Achieve more than 1500 elo in a format",