Unpopular Opinion: Wise, Elderly Impa (i also include the fat one from the Oracle games) > Young, Athletic Impa (both OoT, Skyward Sword and HW 1+2)
Fat Impa is depicted as being fairly strong and muscular. She's not like the regular Elderly ones but more of a combination of strength but older. Basically she's a cross between both version's aspects to a degree.
That said, I prefer Oracle Impa to get in, as she's my favorite design. She's the only actual Elderly variant of Impa who is clearly battle capable in some way. She doesn't look like she's barely able to stand, after all.
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Something like Villager did have options, which is basing it upon items found in the games that they could wield in some way. Wii Fit Trainer had actual poses/athletic moves that were turned into battle-like attacks. Even said Oracle Impa isn't depicted with actual attacks, just clearly looks plausible that she could fight in some way. Something the other Elderly variants simply do not. So it's not a "lack of anything" either in every case. It's just not a popular design either way. Yes, it's true Villager was dismissed at first cause they wouldn't normally fight. However, mindsets change.
Really, for the most part, almost every character got in was based upon something from their own games. Captain Falcon is the only one that really has nothing featured from his own games, even though you can somewhat correspond one special and his general speed at best. He wasn't inspired by some features from his won game, but by Japanese superheroes(it does help his model may have been loosely based upon the original Dragon King model, or a few moves from there also inspired Samus?). Fox doesn't entirely count as he's been seen on foot, while holding an actual weapon, and in-game, uses a vehicle which shoots lasers. It's mostly made up either way, but his moves still has a game basis. R.O.B. uses some moves that are literally based upon the games he was part of, and the rest is pretty much "robot stuff".
Basically, yes, Captain Falcon had no moves whatsoever that were used in any way from his games. Every character otherwise did in some way. ...Well done or not. He's kind of the only case at all where the "has nothing" was a legitimate thing at all, and as I said right above, it might've been a very unique situation that allowed him to be workable. Besides just being a Samus clone, anyway. This isn't the norm either way, so if a character is getting in, it'll be based upon materials that they're remotely capable of in order to create a plausible moveset. They can be mostly made up too. But things like having the right build(model swaps), a design that looks battle capable enough(funny how both of these apply to Falcon, heh), having stuff in their game that can be retooled for a playstyle, or what's going to matter here for them to even dance in Sakurai's head at this point. Oracle Impa aside, the rest of the Elderly Ones don't actually have anything that is easy to work with. Since all they actually do is talk and barely move around. They're just meant for dialogue as an NPC in those games. The other Impas(SS, HW, OOT, AOC, etc.) outright fight or look capable of it. ...I'll note the Oracle one is weird cause it's just the drawn version of the character that is clearly battle plausible, not the sprite. So she's in a weird spot. But again, lol at popularity(Tingle has more, probably so in the West too where he isn't nearly as hated anymore as he used to be).