+1
Yes, easier to implement and consistent with what other series do with form changes.
EDIT: Okay, I've had my sleep. As I said, there are some issues I wanted to bring up. For simplicity's sake, I'll refer to the individual Ascensions as First, Second and Third to avoid redundancy. Second, this may be a lengthier explanation than I would like, but bear with me here since I want to explain this as best as possible to those not in the Fate series. With that preamble out of the way, let's get started, in no particular order.
SLIGHT CHANGES vs. DRASTIC CHANGES: Throughout some characters' Ascension Trees, their outfits and/or forms will gain radical changes. The most notorious example is Antonio Salieri, and perhaps the reason why this conversation started in the first place. post #3867674 showcases all of his forms nicely, with the bottom being his First, the center his Second, and the monstrous form on the top his Third. However, many characters don't have conveniently radical changes to their outfits to discern them between Ascensions. A good example of this is Lancer. His Fate/Stay Night outfit is his First (post #2134826) while a very slight alteration is his Third (post #2134830). His Second is unique to FGO (post #2790953) and easily recognizable enough to tag as such.
A more frustrating example is Mata Hari where we have her First (post #2138498), her Second (post #2587103), and her Third (post #2138497). Can you spot the differences right away? If you said yes, then you're lying. The changes are so minimal that I hardly see the worth in tagging any but her Third since at least the veil is easy enough to see.
You could also throw Archer into this camp entirely, where his First is his FSN outfit (post #2135732), his Second has his hair down and is missing the red clothing (post #2135734), and his Third goes back to the First outfit but has some slight tweaks (post #2135731). It's difficult for me to see any Ascension tags being used for a case like this whatsoever since none of those forms appear to be unique to FGO. The same can be said for Gilgamesh, where his First is basically the golden armor of his uber-popular Second form sans the red cloth around the waist (post #2136694), while his Third is his shirtless form seen in Fate/Hollow Ataraxia (post #4062384). Plenty more examples where those come from, but I'll save that for later.
Anyway, if there's any ambiguity I'd like to see addressed, it's this. Is it worth the trouble hunting down every Ascension form for a character no matter how slight it is?
PRE-FGO FORMS: Many character Ascensions have been carried over from titles that came before FGO. The titles are in release order in the List of Fate Series Characters, so no need to reiterate them here. For instance, Saber's iconic armored dress (post #4752) is treated as her Second in FGO, while that same dress without the armor (post #9276) is her First. Her only unique FGO design is her Third (post #2132774) where a crown and cape are added. See the above example with Lancer as well.
So what does this all mean? Simply put, I see no point in going back and adding Ascension tags for older posts. If a character form already existed in a title before FGO, then I say leave them alone. Just stick to forms that are unique to FGO since the Ascension mechanic started in this game, and we wouldn't want to confuse the issue by retroactively inserting this mechanic to past images.
Generally speaking, an existing character's Third tends to be unique to FGO as an embellished version of their previous outfits. Off the top of my head, I can think of instances like Nero Claudius (post #3022888), Jeanne D'Arc (post #2197364), Child Gilgamesh (post #2344001), or Meltryllis (post #3547873) who have unique Third forms. Those can be tagged just fine, but I believe their other forms should be left alone.
Do you guys agree that we should leave pre-FGO forms out of this, or should they be included? Either way, I believe the Ascension tag wikis need to be thorough about this, OR make an umbrella Ascension tag, imply the three to it, then go into as much detail as we want in the umbrella's wiki, OR write a wholly separate guide similar to the List of Fate Series Characters and link it in the wikis.
CROSS POLLINATION: Inevitably, there are going to be times when Ascension tags are used for multiple characters in an image. Let's use post #3094261 as an example, where Cu Alter is in his Third while Medb is in her First. This means that if one wanted to look for images of Cu in his First, or likewise Medb in her Third, you're going to come back with this image as a result. Using just the three Ascension tags as umbrella tags means this is going to happen, no matter what. However, while it's not perfect, it's a much cleaner and simpler solution than creating Ascension tags for every conceivable character and form. You could say that the three Ascension tags act as filters to help with the search, but users will have to do their own legwork from there.
I don't know if this will be a problem that'll come up down the line, but I figured it'd be best to at least point it out now for future reference's sake.
!!!!AN EXCEPTION!!!!
Sound the klaxons! It's time for that dreaded exception to the rules! There is at least one character in the entire game where the Ascension tags are going to be completely useless, and that is with Valkyrie. As outlined in that wiki, Valkyrie actually changes entire characters instead of just a single person's costume. Ortlinde is the First, Hildr is the Second, and Thrud is the Third, and all of them are already implicated to Valkyrie. In short, they're already taken care of, so leave them alone, period.
Now that I think about it, another really weird instance of this is with the Avenger-class version of Oda Nobunaga. Although it's still the same individual throughout the Ascension Tree, her gender changes for her Second (post #3562482) and is already tagged as Oda Kippoushi. Her Third is a radical change from the other two (post #3555456) and is likewise already tagged as Oda Nobunaga (Maou Avenger). Using the Ascension tags would feel kind of redundant in this case.
All right, that's all I can think of for now. Any thoughts or ideas on how to address these potential problems?