Chapter 2 : On the planet Lavinia. After the vertical has scrolled you will see a base. Destroy these and fly in the hole
Chapter 3 : On the planet Kierke, in the middle you will find bases, destroy them and fly in the hole.
Chapter 4: On the planet Eioneus are there bases which look an eye, destroy them and fly in the hole.
It is necessary to have Nemesis 2 (Gradius 2) in Slot 2 and get all of the Predictions and the item called Crystal Breeze in order to get the true ending.
Operation X: Wrath of Venom is only accessible if Nemesis 2 is in Slot 2.
With one of the Konami Game Master cartridges in slot1 and the game in slot2 you can use the Game Master to start at a higher level and/or with more lives.