The Metroid series obviously needs more reps. But of all options, I am surprised no one has thought of this yet.
The Metroid is the main enemy in the Metroid series. It was created by the Chozo and has the ability to drain the foe's health and float. By contrast, one baby Metroid befriended Samus Aran upon hatching, and this little baby is one of the things that develops the story of the Metroid series. So, it DOES have some significance, but how would it fare in smash?
The Metroid (Wow, I started tree sentances the same way...) should be a light character, able to jump three (Or five, dunno how OP that would be though.) times and float in mid-air. To nerf this, it's air game should be pretty bad, forcing it to fight on the ground. Also, I imagine that if it would get hit by an attack while floating, it would fall into a helpless state like if it just used it's Up B. It should have a mix of mid-range and close-ranged attacks that, while quick, don't deal that much damage. Let's have a look.
A jab: The Metroid lays on it's side and tries leeching the life out of the enemy in front of it, resulting in a flurry attack with no finisher. Every few seconds it will heal the Metroid with 1%, making it very unique.
Side Tilt: This time, the Metroid spins around 360 degrees, a la Ness's Nair, hitting the target with 4 consecutive hits. Deals a maximum of 8 damage, and is really quick.
Up Tilt: I dunno. Maybe some jump upwards like bowser's up smash? Slow, but has decent knockback.
Down Tilt: The Metroid sticks it's teeth out to the side very quickly, poking the enemy and dealing 4% damage, healing the Metroid with 2%
Up Smash: The Metroid flips on it's back, teeth pointed upwards, and chomps on anyone above it. Has a pathetic range, but deals and drains massive damage upon hitting.
Down Smash: I think you'll have to use your imagination for this one. The Metroid first grabs a Chozo while charging that it holds in it's mouth. Then, he slams it down on the ground in front of him, like Robin's Down smash in SSB4. After this, the Chozo disappears. They could also add a second, horizontal hit like Link's Side Smash, with more knockback. This attack can also meteor smash if used at a ledge.
Side Smash: The Metroid charges forward, mouth first, chomping like Pac-Man. If it hits an enemy, it carries them with it until the move's end, where they will be launched. This move has a pretty long cooldown and drains health, but not as much as the up smash, neither does it do as much damage. It does have some good range and knockback.
Neutral Air: A quick spin, which is weak and has pathetic knockback, but can be pulled of very quickly and doesn't last very long.
Forward Air: A weak headbutt. That's it.
Back Air: A chomp backwards, useful for finishing off opponents off-screen. Probably the best aerial the Metroid has, but it doesn't deal much damage and only heals 1-2%
Up Air: By flipping over and spinning, this move deals some decent damage to foes above him, as it juggles the foe upwards. Does not drain any health, though.
Down Air: The Metroid chomps down on anything below it. It should have a long startup and cooldown, but drain a devastating amount of damage to the target below: Maybe 15%?
Before I get into specials...you know how Bowser J.r borrowed some moves from other sources, like hazards and Bowser's hammers? I think the Metroid could have the same kind of specials, with moves from the boss battle with Mother Brain in the original Metroid.
Neutral B: Rinka. The Metroid shoots an Energy-based Ring projectile that can be angled into 8 different directions. If it hits a wall, it will bounce off of it and it's range will reset, making it devastating in stages like Temple.
Side B: Health Drain. By lunging forwards and grabbing on to anyone in range, similar to Diddy Kong's Monkey Flip, you can mash B to drain massive amounts of health from them. For the opponent to get rid of the Metroid, they have to mash the D-pad until they are free. If the Metroid is trying to drain health while the opponent gets loose, it will be startled and open for attacks. However, if the player doesn't mash B when the opponent gets free, they will get right back on their feet. Or...teeth? I dunno.
Down B: Laser Brain OR Metroid Larva. The Laser Brain has the Metroid firing a colorful beam that has decent range, deals insane amounts of damage and lasts for about 4 seconds. However, there is no cancelling the move, which means the Metroid is very vulnerable from the back. It also has a slightly longer delay than, say, the Rinka. The Metroid Larva, a hint to the Metroid Larva in Metroid II, is a mix of a counter and Ness's PSI magnet: Healing it from any attacks but doesn't deal damage to the foe. It does not get healed from Projectiles, however.
Up B: Kihunter. Like the name suggests, this move has the Metroid latching onto a Kihunter, which flies upwards a bit before flying off without the Metroid and leaves it to fall down. If an enemy appears in front of the Kihunter, it will drop the Metroid and start attacking the enemy viciously instead. Similar to the Villager's Balloon Trip, the Kihunter will die if you attack it enough times. If the Kihunter is too big to animate or something, there's also the option of having a Reo lift it instead of a Kihunter.
SUPER METROID SPOILERS
Final Smash: Giant Metroid.This may seem like a bit of a cop-out now, but hear me out, K?
Good. So, the Metroid turns into the giant Metroid from the end of Super Metroid and dashes forwards really quickly. If it hits one person, the Metroid will latch onto them and drain their health until the Metroid's percentage is at 0%. This means that the more damage the Metroid has taken, the more damage this final smash will deal. If the Metroid has taken 90% damage, it will be healed and 90% damage will be added to the opponent's score, which practically guarantees a kill. Since the Metroid is a very light character, it's pretty hard to have a high percentage like this and not get knocked out, making this even more satisfying when it kills.
SUPER METROID SPOILERS OVER.
Other things!
Entrance: The Metroid sits in it's container from Super Metroid, before breaking free and letting out it's cry from that exact game.
Taunt: Either one of the moves that didn't make it into it's Down B: Flashing the Brain Laser around, or hiding in a Metroid Larva for a brief moment.
The Idle animations should be showing of more of the Metroid's "Cute" side, from being with samus.
Idle 1: The Metroid chomps with it's teeth, getting ready for battle.
Idle 2: It floats back and forth for a while, like a cradle.
Idle 3: The Metroid's teeth get stuck in the ground (Somehow), and it struggles with this for a while before it goes back to normal.
I think this would be a surprise addition. I also know that people will probably hate me for submitting this and think that this is "Gimmicky" or "Stupid". And to that I say...Duck Hunt Dog.
HAPPY NEW YEAR!