Mermaid body: Get 10,000 evolution points by the final ocean stage of Chapter 5. Choose "Hand and Feet" and select, "Try to Evolve". Try to evolve three times and you will become a Mermaid.

Bird body: To evolve into a bird in the Reptile Era, go to Mt. Brave and climb up to the top. A voice at the top will tell you to jump down the mountain. Jump off the left side to evolve into a bird in mid-air! The bird is weak at first, but the evolutions for it make it very strong later on.

Secret Cloud Level: In the reptile era, after you've obtained the bird body, wait until the cloud floating around in the overworld stops at a level to the right. Try to enter that level while the cloud is above it. The bird will fly up to the cloud. The cloud is virtually a maze. Get the red crystal that will change the bird into a dragon for a short time. The dragon is extra extra powerful and extra extra strong! The exit in the cloud is somewhere near the top. Use it to reach space. Fly all of the way to the left, which may take awhile. After getting to the far left side, go all of the way up to find an entrance to a large object that may be an asteroid at the top of the screen. Enter it to find an alien doing something to a pterodactyl. He will tell you that he is too busy and leave. Take the object he drops to get 9999 E.V.O. points. Upgrade away! (Teeth and body are the first things you should upgrade. Move to the right to find more openings. Most of them are informational, but one contains a red orb. You can also kill the pterodactyls for +100 E.V.O. points each, allowing even more upgrades. There are also two more asteroids you can enter besides this one; one in the center and one to the right will also contain pterodactyls. In the center one there is a red crystal which will turn you into a gargoyle, and in the right one there will be a green crystal.

Energy refill: To get your HP to the max in the middle of a battle, even the smallest evolutions will make your HP full, like shortening/lengthening your neck, increasing/decreasing body size, etc. Use this strategy to defeat hard bosses.