I've been at Altering Cave for hours (on the right cycle, according to http://www.pokemmocycle.com/) and I've seen over 100 pokémon, but not a single Shuckle.
Am I just unlucky or is there something wrong about its spawn?
Thanks for the help, guys! :)
PS: I'm sorry if this is not the right section to ask this, but I couldn't find anywhere better.