Here is the full list of all 23 Wuppo achievements worth 1,000 gamerscore.
Obtain a Popo Chipcard
Completely cover yourself in dirt
Does Drekel have a shower?
Make an unlikely friend
Buy all gumgumgun upgrades at Betty's gumgum shop
Upgrade all weapons in the game to their full potential
Personalize your gumgumgun's colours
Hijack and vandalize a Popo City tram
Exterminate 800 kneft
Find and defeat all bosses
Find and watch all filmstrips
Achieve maximum happiness
Complete the game
Beat the game on hard mode or higher
Beat the game on insane mode
Complete your first Boss Run
Beat All Boss Run mode under 25 minutes
Defeat Stoplight in All Boss Mode without getting hit
Complete the Boss Run without items from Tein or Raab's stores
Buy Tein Taatseb's helmet during All Boss mode
Defeat the Dustboss by using the Breft2000 suit during All Boss mode
Use the practice mode to fight the fish
Help Raab start his blarb smoothie business