Many Pokemon fans know Arbok from the anime as one of Jessie's Pokemon, often displayed as a weak comical Pokemon that gets blasted away by Pikachu but the Arbok depicted in Pokemon Adventures, specifically Agatha's Arbok, is much more terrifying. This is because it faithfully follows the Pokemon games depiction of Arbok through it's Pokedex entry. Pokedex (DPPt) - The pattern on its belly is for intimidation. It constricts foes when they are frozen in fear. Pokedex (US) The latest research has determined that there are over 20 possible arrangements of the patterns on its stomach. This Pokedex entry speaks of how terrifying it's belly facial-like patterns are and how it can change since Gen 1 and has been a common staple of Arbok's Pokedex entry to this day and to my knowledge this has only been featured in Pokemon Adventures which gives us an idea of how it functions. In the left image is Koga's Arbok which features the original Arbok pattern that we know from the games and anime but in the right image features Agatha's Arbok which has changed it's facial pattern. In the games, Arbok has gained the ability "Intimidate" which is supposed to represent these facial patterns but the Adventures manga takes it a leap further before abilities were introduced in Gen 3. Not only does it terrify Pokemon but Arbok is pretty much immune to facial moves like glare or scary face by changing it's facial patterns to copy those facial moves, such as above where it combats glare by changing it's facial patterns into a glare-like facial pattern. However keep in mind, this is Gen 1 back when Pokemon adaptations were more experimental as Adventures also features Agatha's Arbok having the ability to raise it's own stat depending on other facial patterns.