Talk:Onega Town/@comment-188.174.90.212-20140404211134/@comment-117.222.155.206-20140906061011

Yeah, it is mostly used to complete the pokedex. Beedrill and butterfree are far easier to obtain here than in nagarex forest. Also farfetch'd and ekans can be obttained only here. ekans cant be obtain only in these grottos. If you dont want to waste time in safari for kangaskhan, you can try here.

Once you have entered a Grotto, the Pokémon that is spawned will be "locked" as the only Pokémon you will encounter in that Grotto until Midnight. There is also a chance that no Pokémon spawns and the player will miss an encounter that day unless they reset to a point before they entered the Grotto.

http://pokemonzetaomicron.wikia.com/wiki/Hidden_Grottos