On the subject of Fire Emblem characters, as I saw someone talk about the possibility of more Echo Fighters from Fire Emblem...when you actually think about it, isn't it a bit surprising that they didn't go a bit of the Bowser Jr. route with Marth or Lucina?
Cause out of all the Fire Emblem character movesets, Marth and Lucina's are the most copy-able, with Chrom's being second. But like from Marth and Lucina, you could get some of the other Lords as easy Echos/Alternate costumes, like Seliph, Eirika, Eliwood, Elincia, and some of the other one-handed sword wielders, like some of the later Mercenary characters like Inigo, Severa, etc. And it makes sense cause most of the early Lord characters were made to be very similar to Marth gameplay-wise.
In the case of other Fire Emblem characters:
-Chrom is the 2nd most copy-able as his moveset removes the issue that Roy would've given, which is the fire effect. The fire effect is what also makes Ike hard to copy, as no other Fire Emblem character would be able to do Ike's Eruption aside from maybe Eliwood, due to Durandal being the Blazing Blade.
-In Robin's case, while Mages are very common in Fire Emblem, Robin wields both tomes and a sword, which many Mage characters often do not unless promoted to a class with both. And very often, that class is Dark Knight, which uses a horse. Robin is the most notable exception of being an Infantry unit that uses both Swords and Tome, aside from their children in his game. On the other hand, if they do go that route in a remake, Mark from Fire Emblem 7 could be a potential costume/Echo fighter for Robin.
-Corrin would not be able to be copied, due to the nature of their dragon transformation. While there are dragon characters, none of them can transform just their limbs and whatnot compared to Corrin.
-Byleth probably can't be copied, as his moveset was created in tune to represent Three Houses. Like it's not easy to imagine other characters having the same moveset as Byleth.