Updated CPSIA Certificates from Nintendo have confirmed that Lucario, Charizard, Marth, Toon Link and Sheik amiibo will be restocked soon for Super Smash Bros. Ultimate. An exact date has yet to be announced by the publisher, but stay tuned for any updates. All current Super Smash Bros. series amiibo figures are compatible with Super Smash Bros. Ultimate, and any fighter’s amiibo figure from other series will also be supported.
Source: Nintendo Support