Never played BE, but the spritework looks amazing. I am not too aware of the technicalities of 6's port, but I do not know if that would be doable given 6's rather small sprite sheets (e.g standing, swing, etc only having a few different sprites to them). I hope to be proven wrong though, or to just have those sprites with the old animation style (anything over the current abominations)

Here's also sprites for other characters.
http://cdn.wiki.famitsu.com/theme/famitsu/ffbraveexvius/%E3%82%AD%E3%83%A3%E3%83%A9%E7%94%BB%E5%83%8F/unit_ills_206000503.png

Also the list of sprites from Brave Exvius
https://www.spriters-resource.com/mobile/finalfantasybraveexvius/

They look really nice (especially Kefka). Shame I can't see a couple of them, like strego, relm, gogo or umaro