Leaving the Pokemon alone, you continue walking around, only seeing large holes, craters and hills. As you walk towards one hole, you hear a rumbling from below but you think nothing off it. Coming ever closer, the rumbling becomes more constant and instead of being fearful, curiosity springs up and takes hold of you. Coming to the edge, you peer down but back away quickly enough to see an Onix come out, with a Rhyhorn and Kabuto quickly behind him:

Feed/Throw Rock/Run/Throw Ball/Attack/Chase/Trap/Get Closer

All you can do is walk around or climb one of the hills