This is my tier list for the special weapons of Mega Man V. As the previous four lists, order within the tiers is based on the order I obtained the weapons, not their quality. It took a while to release because I got distracted by other games, including but not limited to finally beating the Mega Man game I couldn't beat as a kid... Mega Man 9. As a whole, I find this set of weapons to be stronger than Mega Man IV's middling set, but weaker than Mega Man 9's powerful set (I have no plans to make a tier list for the MM9 weapons). The tiers here are A-, B, and C+ because this game's most and least useful weapons are closer in utility to eachother than the most and least useful weapons of the other GB games.
Grab Buster: Healing on demand is excellent, but this weapon has reliability issues. If you miss, shoot something that doesn't drop an item (e.g. the bubbles that Feeburs make or Baby Flies that haven't fully split), or run into an immunity (which is likely, because all bosses are either some level of weak to this or outright immune to it), you don't get an item drop. On top of this, it's possible for the item to miss you and fly offscreen, especially if you're trying to dodge an enemy's attack while it's flying towards you. These issues do not prevent this weapon from being extremely useful.
Bubble Bomb: There are plenty of airborne enemies worth shooting with this, and it deals with the Hueys quickly. On top of excelling in its role as Jupiter's weakness, it can hit Pluto when other weapons can't. However, how Shuhorns are immune to it is disappointing, and its ability to crawl along walls is mostly useless to the point where you want to avoid using it.
Salt Water: The attack angle of this weapon is excellent, making it easy to deal with enemies below (but not directly below) you and Monkikis. On top this, it's capable of multi-hitting. How Mars, Punk, and the Right Knuckle are weak to it is quite useful, but Mercury's secondary weakness and the Left Knuckle's primary weakness don't matter because those fights have enough downtime to make charge shots work just as well, and it can have weapon energy issues.
Spark Chaser: Everything the Bubble Bomb does for you in stages, this does better, and the same goes for hitting Pluto when he's hiding in the corner. Neptune is weak to it, and it's an excellent non-weakness option in the Venus refight because it'll home in on and pierce through his Bubble Bombs. Of the four weapons Brain Crusher phase 2 is weak to, and the wide variety of weapons you could use on Sunstar, the homing makes this the best option in both fights.
Black Hole: How it pulls small enemies in gathers their drops, which is quite useful for a screen clear weapon to have. The outward explosion means that it doesn't only kill small enemies. I'm not gonna hold how I missed that Mercury is weak to it against the weapon, but I will note that Mercury's weakness is only applicable in the refight.
Electric Shock: If you want massive damage, this weapon delivers, dealing more damage than a charge shot; this is most apparent when you consider that it can one-shot an Ou-Ou when a charged shot can't. It's also the best way to take on Hell Metall DXes, and the way it interrupts Saturn's attacks is the strongest weakness in the game.
Tango: Tango's attacks are, in practice, an alternate charge shot that's mostly useful for hitting enemies below you, striking angles that the Salt Water can't and vice-versa. He burns through weapon energy too fast for keeping him out long term to be practical, but this isn't a problem because doing so is unnecessary; you can recall him as you please. However, as you get more options, he begins to get outclassed; answering the second phase of a Hell Metall DX is great, but the Electric Shock can deal with both phases in one shot once you get it.
Photon Missile: In stages, how long this weapon takes to move forward makes it only really useful against enemies that charge straight towards you, and even then it'll become obsolete in that role once you get the Electric Shock. It makes up for this with excellent performance in boss fights. Venus, Dark Moon, and Quint are all singularly weak to it, Ballade and Brain Crusher phase 2 are both weak it along other weapons, and Neptune and Saturn have meaningfully useful secondary weaknesses.
Deep Digger: As an attack, this weapon is only useful exactly once, in the Terra fight (it can't deal damage in the Uranus refight, but it can dig a hole that you can fall into and die. I learned this the hard way). Despite this, the collectibles you can obtain by using it, including but not limited to 3 of the crystals, are quite helpful. Since you can shoot uncharged shots with it selected, you can fight back if enemies attack while you're trying to dig something out.
Break Dash: How this attack is an alternate charge shot makes a whole lot more practical than the Charge Kick. This is most apparent when you use it on Uranus; striking him with Break Dash itself is only practical when he jumps towards you, but you can keep the pressure up with uncharged shots until then. The invulnerability is nice against Metall Snipers, Biribarees, and Piriparees when they aren't standing on the edge of a platform as the latter two so often are. Hitting Punk with a weakness would be really satisfying for the same reason I didn't think to try it (he's immune to special weapons in III), and it worked well enough against Ballade that I didn't wonder if I got the weakness wrong (I tried it first because the Break Dash, as a charging weapon, seemed like the weapon in this arsenal most like the Pharaoh Shot).
My boss order was Mercury, Venus, Neptune, Mars, Uranus, Pluto, Jupiter, Saturn. I used a password to replay Mercury's level with the other three boss weapons, but instead of doing that for Uranus's stage, I just replayed it normally as part of acquiring the last crystal.