Heres some additional ideas on things that could have rewards upon completion:
-Completing all quests (on /quests)
Reward ideas: hard cash money (cuz holy fuck the amount of time youd have to spend on that is absurd), prefix, idk
-Completing dex (rn its bugged and doesnt show u have 100%)
Reward ideas: prefix, idk
-Completing shiney dex ( )
Reward ideas: also prefix, leggy key?, idk
-Collecting all alcremies?
Reward ideas: prefix, money, idk
-Collecting all vivillons?
Reward ideas: prefixxxx, munie, idk
-Collecting all server texture mons
Reward ideas: prefix (bro why do i want prefixes for all of these), munie?, Idk
-Will add more if i think of more