When you finish fighting Magolor's 1st form, you have to lose your power to get the Super Ability and Magolor deletes the Ability after. Magolor Soul will throw out enemies as his 1st or 2nd attack. If you chose an ability from the ability room before the battle, the 1st enemy Magolor Soul throws out is the ability you were using before.
There are secret rooms in 1-2, 1-4, 5-5, 6-5 and 7-3. In 1-2, go to the room with the Needle Ability. To the right of the room, there's a Maxi Tomato. In the place you find the tomato, fly to the top left. There's a hole with a secret inside. 1-4, go to the end of 1st room to the edge of the screen, then backtrack. You'll see a hole that wasn't there before. There's a door, enter it. 5-5, In the 1st room, climb the tower, don't enter the door, fly higher. Enter the barred door. 6-5, Go to the end of 3rd room (Rooms include crushing stages) where Halcandran Waddle Dees fall off the conveyor belt. Climb the conveyor belt until you reach the dead end. Enter the hole in the net-like background. 7-3, Go to the goal room, but don't enter the finishing door. Fly directly up to the meteor in the background. Enter the meteor.
Hal rooms are rooms hidden within the game by Hal. Labrotory
The first one is much harder to find, as you have to go as far as right as possible on 1-4, then back-track to find a section of ground has lowered. This HAL Room is amazing for granting access to four superb abilities VERY early into the game.
The other room is found on 6-5 and isn't as well hidden, but still pretty easy to miss if you don't bother to explore that cranny. Where the little magolor like things fall go in that tight area go to the right enter a door which is kind of in the background