Chrono Trigger Cheats

Go to Guardia Forest in 600 AD. Once inside, take the first right and go to the upper path. While in the small clearing, you'll notice a bush in the upper left. Go next to the bush and it will begin to shake. Press A and a monster will pop out, leaving a Shelter as he runs away. Get the Shelter, and then leave the forest and reenter. Do this until you have as many shelters as you want.

When on the black omen, you will come across a Blubber Hulk (which at first looks like a tornado on the ground). Approach it and have Ayla use Charm which gives you the strength capsule. Run away and go back through the door you came through (with the two Nus) and repeat.