Mama Turtle Room
|Fish Tank||Adjacent rooms|
The easiest method to collect the Energy Tank is to charge a shinespark, then jump off the ledge towards the center of the room, and spark up. The fastest way is to charge the spark while you open the red door, but you could alternatively open the door, then charge the spark through the room transition.
If you end up standing on the Energy Tank's platform after collecting it, you can run off the ledge to the right, angle down, and fire to expose the missiles, and you'll collect them. You'll likely need to stand left of the center of the platform to get enough run speed for this.
If you don't have Gravity Suit or Speed Booster, you can hit one of the baby turtles in order to get Mama Turtle to get enraged, spinning around the room. Then stand on her back, and she'll fly up out of the water, high enough that you can use Grappling Beam to latch onto the block below the Energy Tank, or that you can Infinite Bomb Jump up. If you do Bomb Jump up, you'll need to make sure that you're not standing directly under the platform, or else you'll need to start over.
If you have Hi-Jump Boots and Speed Booster but no Gravity Suit, you can jump from the top-left ledge in the room, then walljump off the side of the pedestal.