The entire selectable character roster can be access through gameplay & NOT through Amiibos.
As you mentioned Wario. If you have a Wario Amiibo, you'll be able to have Wario as Figure Player... but it will NOT instantly unlock Wario in the game. You still have to hit the conditions for the unlock battle for Wario (the easiest option is just playing smash battles, as you'll get an unlock chance every 10 minutes).
Please be aware that if fail an unlock chance, you'll have to wait a couple of minutes before you can select the "Challenger's Approach" (which appears in the Smash Menu in the Vault section, IIRC), so you can rematch each character you previously lost in series. If you lose again, you'll play for about 10 minutes for the Challenges Approach door to reappear.