For skills, i think it depends
i mean, let's say that Chrom gets for his default moves... i dunno, Luna, Aegis, and adaptations of Aggressor and Charm. All skills he can get.
but as CUSTOM MOVES, it wouldn't be that weird to see Chrom with, respectively, Astra, Pavise, and adapted Vantage and Anathema.
The only skill i can see Chrom getting for his default moveset that he doesn't have is Pavise (because Aegis is anti-projectile and they might wish for anti-melee) or a Rally skill (because Chrom only has the super useless Rally Skill, and the Strength/Speed/Defense versions could work better for moves)
As for weapons, think that under the weapon switching mechanic i suggested, Swords, possibly a single Axe, would be alright (note: Rapier and Silver Sword, which are canon weapons for Chrom, are what his defaults would be. the rest would be custom moves).
If not, the only sword that has any business being in Chrom's moveset besides the Falchion, is the Rapier. 3 normals would be enough, i think.
for Lances, i think throwing lances are the only truly viable thing for Chrom; and this would also open room for a throwing Axe (and if they are feeling funny they could even let his use the Ragnel...). Bows could be used in the same vein, but i don't think Chrom should have so many projectiles, so it's either Lances or Bows; and we have Bows already. 3, in fact (okay, 5 with Shielda's FS)
They could make Chrom's bow more unique by making it stronger, able to be aimed in the same vein as the metal blade, and working like Pk Fire/Needle in midair.... all in exchange for a limited amount of uses.
As for your "playstyle" comment, few specials ever significantly impact a character's playstyle besides recovery moves since they are intricately linked with that.... I mean, we have the good projectiles that set things in stone with camping/Approach, Rest and...?
... before the greninja direct, i was hoping for that pair-up between Chrom and Robin, and when you played as Robin, Chrom would stand back and use his bow from the background. Would be a nice reference to postgame Chrom... and it would fit Robin's playstyle better than an awkward Jaelin/Hand Axe from the background.
Astra I can kind of see (though Chrom can't learn Astra, it's a Swordmaster skill).
Vantage (which he also can't get, as Chrom can't become a Myrmidon) is just wrong. There is no way to make Vantage viable in Smash, you're basically giving an entirely different ability the name Vantage.
The closest thing you could do to make a viable Vantage would be to have Chrom's move priority increase the higher damage he reaches. Which is an absolute nightmare for balance and implementation.
This is the problem. All of the "skills" are just modifiers to the standard attack system. 90% of them don't even make any sense in Smash. Reduce enemy Defense when attacking? Increase Skill by 2? Gain a free Small Gold when you slay an enemy? They just really don't work.
The most viable skills are ones like Astra (which could play out as a Dancing Blade clone, you're right), or something like Vengeance, which could be a unique attack that increases power the higher Chrom's damage is.
But none of them translate directly, and changing them too much just loses the entire point.
wasn't that done with multiple Pokemon as well as the mother boys before? I definitely don't remember Pk thunder involving hitting yourself for an human missile attack that move is particularly egregious because actually controlling Pk thunder is against all that it was before, iirc.
As for Vantage, your idea is nice but, would it be broken if it worked like WFT's Deep Breath? a temporary buff move that requires some setup? I don't think it would be that broken then, especially since Smash's focus is FFA 4 Players items on, which is a hard envrioment for these kind of moves (as my casual experience with PM"Lucas and his Offense Up move tells me...). Of course, in 1vs1 serious business you'd only have time for that once your opponent dies; but considering the enemy starts invincible...
Of course, that's assuming your idea would be the one chosen. Maybe it would be simpler than that, as a more flashy Counter move? Sakurai talks so much about uniqueness, but he ain't afraid of shoving a counter on 4 of his newcomer (Ok, Lucina is a clone, and Greninja is aesthetically different enough... but Palutena had no business with Counter being the default move, seriously...). Sure, with this same example you could mess with the counter a bit to turn it into something a little more unique (like Peach's), but i dunno.
I think Vengeance would be better fit with my "weapon switch" idea, as a custom move (the Vengeance axe). maybe as a custom move of Luna or another buff custom over charm or a rally skill.
... Armsthrift could surprisingly work well with my idea of Weapon Switching, especially if chrom also has 1-2 ranged weapons with durability issues.
It would be an awesome mechanic, admittedly. Balancing nightmare, but that's on Sakurai and the balance guys, we can hope for it all the same.
The main problem with it, however, is that it doesn't actually change the play style. None of the skills do. This is the problem with them. You can add all sorts of really awesome mechanics and effects like this with skills, but none of them change the fact that Chrom's a fairly generic swordfighter when it comes to moves.
Plus, he can't get most of the better skills to implement this way. The best ones to give him would be the ones he is guaranteed to get. Unfortunately, Charm is unviable in Smash, as is Dual Strike+ and Righteous King. And Aether has been done already.
If he had picked up Vantage as his first skill and used it through most of the game, it would make sense to make that a core mechanic of him in Smash. As something used by an optional class for him, it doesn't really work. As something used by a class he can't become, it doesn't work at all (though it would be awesome for Lyn or Lon'qu).
None of the skills he can learn really lend themselves to a core mechanic, unfortunately. Skill +2? Useless. Prescience? Hit Rate +20? Nope. Bowfaire? Ha, no. Bowbreaker? Nope. Rally Skill? No. Discipline? Useless. Defender? Useless. Outdoor Fighter? Almost all maps are outdoors, and would ruin balance. Aegis? Possible, but utterly ruins balance by overpowering him against certain match ups. Luna? No way to implement. Dual Guard+? Completely negate some percent of attacks? Massively OP.
That's the thing, the skills just don't translate well. If he had one of the half dozen that actually work, I'd give it to him in a heartbeat. But he doesn't.
none of the skills would work with a 100% canon transference, the same applies to most stuff seen with every character in smash besides Megaman; and even him got some adaptations for his smash attacks. As long as they don't completely **** on what the moves stood for (PK Thunder, Rest, Confusion, Double Team, Din's Fire, Egg Toss, and in a roundabout way, Paralyzer) Luna could work as a charge attack which could be cancelled into a damage (and shield damage) buff. Charm would have to be a speed buff move to reflect Hit/Ddg bonuses, as would Rally skill and Prescience. That's just one idea: Marth's Shield Breaker was based on similar stuff and we even had two versions of that. it would be interesting to see Luna as a reworked Melee!Shield Breaker; especially if Chrom is more Slash-based than Swing-based, or something completely new
after seeing what was done with Rest, i don't doubt anything.
If Nayru's Love worked, i do not see the deal with Aegis. None of the reflectors are broken if used only as reflectors, i do not see why Aegis would be any different.
in Melee, Brawl and Project M, and I safely can say that removing 
