Where to Find Hippopotas in ARCEUS
There is a female and male form for the , and essentially the difference between them is that their colors are inverted. One is dark brown with light brown spots and the other is light brown with dark brown spots.
The easiest place to find a bunch of would be Sludge Mound in Crimson Mirelands, which is southeast of the Bogbound camp. Watch out though as there’s a pretty nasty level 58 Alpha Hippowdown also guarding the bogs.
Once you’ve caught a female and a male (keep checking your Pokédex to track), head back to Anthe and show her them. Upon completing this request, you’ll unlock more clothing options to purchase at her shop!