| Pulling a Chrom that was -Atk really made me think of useful niches that he could provide without his sky high attack stat. This Chrom build has a specific niche that only he can do: be an anti-dragon Galeforce unit.
IVs: -Atk is actually not that bad for Chrom. As stats go, he can't really dump any of them. His three stats that are super-banes (Spd, Res, and HP) are all very useful against dragons: -HP will result in definitely getting affected by  Panic Ploy 3, -Res will reduce his ability to take hits from them, and -Spd means he will be unable to proc  Galeforce. -Def is reasonable, but it would be detrimental against Myrhh making Chrom unable to double her unless he had already taken damage. -Atk is still reasonable, leaving Chrom at a respectable 34, more than enough for what he's going to be doing. Additionally, -Atk can mean the difference of attacking once or attacking twice, which can determine whether he can charge Galeforce or not.
Weapon: The Sealed Falchion gives Chrom a notable 5 pt buff to all of his stats when his HP is below 100%, while also giving him dragon effectiveness. It is necessary for this build.
Assist: The advent of Chill Skills and the ubiquity of Panic Ploy makes Harsh Command much more viable in the meta, especially on Cavalry, where emblem buffs are a vital tactic. Alternatively,  Reposition is another assist that helps movement.
Special: Chrom can use Galeforce to hit multiple dragons on the same turn effectively crippling the opponents team. It is necessary for this build.
A: Chrom comes with Fury right out of the gift box. Making up for his bane in Atk or Def, it fixes his terrible resistance and makes him a bit faster. It also triggers his weapon's effect.
B: Chrom is bulky enough to use Guard well. He doesn't need a skill like  Desperation 3 which B!Roy and Siegbert need to use, because he is much bulkier than those two and can take a hit, even from Dragons. Guard on the other hand, is much more useful to Chrom because he will be fighting Dragons, which more often than not, run  Steady Breath. Guard will save him from eating a special, simply because it will prevent Steady Breath from working. This makes Chrom's fights against dragons much easier, improving his matchups against Nowi and other blue Dragons.
C: Cavalry teams need emblem buffs. Hone and Goad are arguably relatively more useful than Ward or Fortify. Goad Cavalry is notable because it triggers in an area around Chrom after he has attacked which can help his mates clean up after him.
Sacred Seal: Heavy Blade is an engine that enables Chrom to trigger Galeforce faster than normal methods. Chrom's Attack is high enough to proc it consistently due to Fury making up for his bane, and Cavalry buffs.
Good Teammates: Chrom appreciates support that allows him to remove two enemies safely. Healer support can be beneficial to Chrom, allowing him to be a bit more reckless. Mages help Chrom fight non-dragons with high defenses (Armor emblem). Notably, LA!Lilina [+Atk] with only Hone Cavalry buffs can remove  Wary Fighter 3 Effie using  Gronnblade+, which is a huge service to Chrom. | 
Optimal
All-purpose
Very high investment
Cavalry
Creative
Chain
Medium investment
High investment
Arena
