While obviously Alm and Celica's amiibo have the biggest effects in Fire Emblem Echoes, other amiibo do work with the game. And apparently Daisy's amiibo is one of the more useful amiibo from what I've heard.
The non-Fire Emblem amiibo don't actually all do the same exact thing in Fire Emblem Echoes. You can summon illusory soldiers in battle depending on the amiibo you use. Some amiibo give you more than one soldier, such as Toad.
Using Daisy's amiibo will grant you one Dread Fighter. I do remember the Dread Fighter being a pretty good character class in Fire Emblem Awakening (the only FE I've played).
I don't own the game and this is just information I came across online. Looks like Daisy has some more use after all.