Fire Emblem Echoes: Shadows Of Valentia is amiibo-compatible, but not just with the new Alm and Celica amiibo. You can use pretty much any amiibo you own with the game and it'll have an in-game effect. So let's go over just what you get with each amiibo.
Unique Alm and Celica Amiibo Bonuses
As the the two amiibo figures released alongside the game, it's hardly surprising these two have the biggest effect on Echoes. Both Amiibo come with their own unique dungeons for you to tackle. Alm's comes with a Duma dungeon while Celica's is Mila themed. Both dungeons are essentially a series of difficult enemy encounters, but you get some nice loot for each character if you stick it out to the end.
All Other Amiibo Bonuses
Both Alm and Celica can use their Turnwheel in battle to summon an illusory soldier with a unique build and stats depending on what Amiibo you stick on the 3DS. It costs 10 HP to summon a soldier, they only last a single turn, and they act on their own accord, so it's probably best to save this feature for mid-game if you use it at all. We took all the Amiibo we had in our vault and used it with the Turnwheel to see what came out. This isn't every Amiibo that's out there, but it's a lot of them. Here are the soldiers and stats you get for each figure. Some amiibo give you multiple soldiers. Those figures will have a number next to their name in parentheses that represents how many units you get.
Alm Amiibo (1 Fighter)
Celica Amiibo (1 Priestess)
Marth Amiibo (1 Lord)
Samus Amiibo (1 Cleric)
Super Smash Brothers Bowser Amiibo (1 White Dragon)
Smash Hammer Bowser Amiibo (1 Necrodragon)
Super Mario Series Donkey Kong Amiibo (2 Barons)
All Mario Amiibo (3 Mogall)
All Princess Peach Amiibo (1 Necrodragon)
All Luigi Amiibo (2 Snipers)
Daisy Amiibo (1 Dread Fighter)
Yoshi Running Amiibo (2 Gargoyles)
Glow In The Dark Boo Amiibo (2 Cavalier)
Toad Amiibo (3 Witches)
Kirby Amiibo (3 Mogall)
Waddle Dee Amiibo (2 Paladins)
For more on what amiibo from Legend Of Zelda, Splatoon, and more will get you, head over to page 2.