Before we shove everything into an A tier, let's bring some moves back down to earth.
Can't cancel the move during charge, easy bait for a reflector. And air approaches are completely safe whether he throws early or goes for the full charge. It can still bait an approach, but If I'm ahead a stock and Greninja throws tiny shuriken at me from a safe distance, I'll stand my ground and block or avoid every one. It's not at all like Samus or Cloud's Limit charge where they're getting more dangerous as I leave them alone. The fully charged shuriken also has some unique problems. Before its final hit, it deals just 0.6 damage, which is very low priority. Ganon and Bowser can get clean through it with their dash attacks, hitting Greninja and not taking damage from the projectile. Ganon and Falcon also have Down B. But if you try an attack that doesn't deal 9.6 or more damage, you will get caught by the rest of the attack. Finally, when you block the full shuriken, you can dodge roll out of the multihits. An issue so prevalent that Greninjas regularly prepare for the dodge chase. Blocking full charge shuriken isn't ever ideal, but having this way out of danger is a serious flaw in the move's design.
Can cancel into shield...but not on frame 1. Once she charges the first needle, Sheik must perform a 8 frame transition before shield comes up. I should point out now that she does have frame 1 dodge roll by pressing left and right during charge, but it's a poor mixup choice. Her only alternative attack options being throw current needles, pull up shield and grab (14 startup), pull up shield and short hop aerial (15 startup). And really, needles aren't threatening to get hit with. 7-11% damage is a lot for her toolkit, but she's not a character with an abundance of kill moves and setups. Tacking on some extra percent is a miniscule step towards earning the next stock. And again, the opponent should only be baited if they're trying to earn a stock lead. Plus a full barrage of six needles still allows time for a guaranteed dash grab if you're within range after blocking. And if the victim is 0 to low%, needles deal such little hitstun that you can still have frame advantage against her after taking a hit. So getting in close while she's charging can benefit you whether you block or get hit.
The only other charge up move that lacks a frame 1 shield transition, in case anybody was wondering. I don't have a frame data source to back it up, but I assume his transition is 8 frames, plus whatever it takes to finish the current wind. So 8-20, going by Brawl's frame data. That being said, I like giant punch's design a lot, even when all it affords DK tool kit is something to force approaches with. C feels appropriate.
I don't see this as A tier. In fact, I don't think it's even B. Being able to shield cancel is about the best thing for this attack. Because unlike other projectiles you can pick up the nut out of the air and use it as your own. Mega Man has that issue too, but there are few truly scary applications for Metal Blade that involve throwing it directly at the opponent. Peanut Popgun's explosion from full charge is Diddy's strongest individual attack in terms of knockback, but the projectile itself is low reward and wouldn't gimp recoveries if it did hit.
Come on guys, everybody knows how to deal with this one. Blocking it results in 7 + 3 shieldlag/shieldstun. 17 frames total before you finish putting down shield. Meanwhile, getting hit by the fireball incurs about 3 frames of hitstun and doesn't move you more than an inch away. Even at high % the result won't scale much. Luigi wants to use this move at maximum range in order to blockstring a dash grab, so stay out of that range. If you're lucky enough to have closed in before getting hit, that's a free smash attack, dash grab, whichever move lets you inflict the most violence to make up the 6% damage. You can also stay out of its effective range and fire/charge projectiles of your own. It's a good projectile, whose slow travel speed matches Luigi's slow movement, but quickly becomes less threatening once you understand the point of it. Perhaps better than C tier, but certainly not A.
I really don't see a point. Marth/Lucina's shieldbreaker has massive range and deals extra shield damage. Roy has ten less endlag on his move, but what do you accomplish by landing this 23 startup attack anyway? Instant kill on a full charge is nice, but for a shield break scenario, just push them to the ledge and you'll only need them to have about 25% damage for full charged Fsmash to secure the stock. The hitbox is tied to the explosion and not the sword, allowing for good horizontal disjoint but not vertical, defeating the potential for this to be an alternative Fair. I see this in D.
How often do we see players use this? The projectile itself does not give her shield/dodge rolls while charging, and a reflected full charge can kill rosalina extremely early. Rosalina and Luma are much safer and threatening when both characters are together. Separations happen when Rosalina gets hurt, not because the player put him somewhere else. By firing Luma away from you, you invite the opponent to kill Luma while he's alone and far away from Rosalina. Normally, you have to get a hit in on her in order to have such an advantageous state. Plus the move does absolutely nothing if no Luma exists. I've a theory for how this could have been a good move. Have it so you can place Luma right where he is with an animation as fast or faster than the recall. This would allow you to use Luma as a positional hazard and get those sweet benefits from Luma being separated. But as is, I see this being D at the highest.
I stand by what I said earlier. This attack has zero place in his moveset by being the second strongest attack for a shield break scenario. Also, with 17 years of smash bros, do people still smirk when they see a falcon punch? I award it no style/hype points. Falcon's neutral B is the worst in the game, rivaled only by Jigglypuff's in my opinion.
Similar to Arcfire, Arcthunder can be dodge rolled out of if you block it. I see people wait out both moves all the time in their shield and it makes me mad. Since Arcthunder uses a quarter of the tome's durability, it's worth the ground you've lost by dodge rolling away. But I also would put Robin in A. 4 choices of projectile and all are good to great. And having both this and the fire tome lets you zone almost forever if you remember to favor one over the other at a time, mitigating the issue of tomes needing to recharge. Fire relies on Thunder while Thunder in turn relies on Fire, it's good design.
Edit: oh and
. It's a move whose utility is 100% dependent on the matchup. Most characters in the game have some projectile yes, but are they all worth it? Even if you wanted a single sheik needle or ember from Flamethrower, Villager must finish the pocket animation before its stored. So if you grabbed a sheik needle from a barrage of 6, the 6th would hit you, and you end up with no needle. People say pocket is no problem if you just stop using projectiles; that the other character is really in control of this threat. But the ultimate result of that mentality is still that the opponent loses entire moves from their set by choice. So the existence of Pocket matters regardless of how the other person plays their character. That's powerful, but I have no idea where it should rank when all its applications are unique to specific scenarios. But A seems a bit high when you can name matchups in which Villager effectively has no Neutral B.
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I do find 
Oh & even if you leave the jumpsquat period & are gonna be airborne on frame 6, inputting Straight Lunge on frame 6 still "jump-cancels" & has Little Mac grounded again. So uhh, cool I guess.
