I don't know if the article I made will be deleted, so I won't be working on that article any further. Instead, I suppose I'll just take what I wrote and post it here in this blog.
Metroid II: Return of Samus lacked stacking.
Unlike the previous Metroid games, Super Metroid implemented stacking on a higher level. All of the beams could be used simultaneously. However, if Samus was using the Spazer Beam, she would not be able to use the Plasma Beam, and vice versa. Nevertheless, there is a certain method that would allow Samus to use both the Spazer and Plasma Beam simultaneously.
Samus was also able to use the Varia Suit and Gravity Suit, allowing her to resist heat damage, reduce attack damage, move freely under water, as well as magma. Interestingly, if Samus was to unequip the Varia Suit and leave the Gravity Suit on, she still would not take heat damage.
In Metroid Prime, Samus is able to combine her Varia Suit and Gravity Suit, much like she did in Super Metroid. There is also a new type of suit called the Phazon Suit, which protects Samus from blue Phazon. In the end, Samus is resistant to heat damage, can move freely under water, and come in contact with Phazon without taking any damage.
Like Super Metroid, Metroid Fusion allows Samus to combine all of her beams and suits. Samus is unable to switch her upgrades on or off, however.
Fusion is the first Metroid game allowed Samus to stack her missiles.
Metroid: Zero Mission is much like both Super Metroid and Metroid Fusion, except that Samus is unable to switch her items on or off.
Technically, as far as beam weapons go, there isn't any stacking. Still, the Annihilator Beam can be considered a pseudo-stack, in that it requires both the Light and Dark Beam to be used. It is capable of opening portals, harming creatures of both Aether and Dark Aether, and energizing Light Beacons and Light Crystals. Still, it is incapable of opening White and Black Hatches.
Although Samus collects Affinity Weapons in Metroid Prime Hunters, none of the upgrades Samus collects can rightfully be considered stacking.
Metroid Prime 3: Corruption is the first of the Metroid Prime trilogy to use stacked beams. It is also the first of the entire Metroid series to stack the Grapple Beam. The Seeker Missile was also used in conjunction with the Ice Missile. Interestingly, the Hyper Beam does not have the effects of neither the Plasma, nor Nova Beam, making this weapon lack stacking.
Metroid: Other M continues with the same features as in Super Metroid and Metroid Fusion.
- Like Metroid and Metroid II: Return of Samus, Metroid Prime and Metroid Prime 2: Echoes are the first two of the Metroid Prime trilogy where there is no stacking beams. And like Super Metroid, Metroid Prime 3: Corruption is the first of the trilogy to introduce stacking beams.