Here is the full list of all 40 World's End Club achievements.
Cleared the first stage
Cleared all stages in the Reycho chapter
Cleared all stages in the undersea theme park
Cleared the Kagoshima Area
Cleared Oita Area
Cleared Fukuoka/Yamaguchi/Hiroshima Area
Cleared Aichi Area
Cleared Hyogo Area
Cleared Osaka Area
Cleared Kyoto Area
Cleared Nara Area
Cleared Mie/Aichi Area
Cleared Gifu/Nagano Area
Saw Ending 1
Saw Ending 2
Reycho's hidden abilities awakened
Mowchan's hidden abilities awakened
Chuko's hidden abilities awakened
Nyoro's hidden abilities awakened
Pai's hidden abilities awakened
Kansai's hidden abilities awakened
Jennu's hidden abilities awakened
Tattsun's hidden abilities awakened
Aniki's hidden abilities awakened
Reycho threw 100 times
Mowchan hardened 50 times.
Chuko ate 50 bags of Karamucho
Nyoro invented 30 times
Pai used a force field 100 times
Kansai swung 100 times
Jennu stuck on the ceiling 50 times
Tattsun transformed into Electro Ranger 30 times
Aniki shook the ground 20 times
Cleared all the stages in the Pochi chapter
Collected all the stickers
Cleared the school stages in the Tokyo Area
Cleared the desert stages in the Tokyo Area
Cleared the panopticon stages in the Tokyo Area
Cleared the HEAVEN Area
Experienced the true ending