Many of the secret characters can be earned by collecting 6 stamps from the daily missions. In order to do this, complete your day’s mission every day, and do this for six days in a row. Here are the secret characters that you can collect from each set of daily missions.
Yax (Zootopia) – Daily mission reward for six stamps.
Nangi (Zootopia) – Daily mission reward for earning six stamps.
Bandersnatch (Alice Through the Looking Glass) – Six Stamps Reward.
Doom Buggy (Haunted Mansion) – Six Stamps Reward.
Ed (The Lion King) – This is also one of the daily mission rewards for collecting six stamps.
Tadashi (Big Hero 6) – Collect six of the daily mission stamps.
Yokai (Big Hero 6) Collect six of the stamps for completing daily missions.
Sour Bill (Wreck It Ralph) – Another one of the six stamps reward characters.
Roy (Wreck It Ralph) Can also be earned by collecting six stamps.
Once you complete one of the six stamps reward sets and earn a new character, your daily missions will reset. Once your missions reset, you will be able to do this all over again. Keep doing the daily missions in order to earn more and more of these hidden characters. Shout out to Disneology.com for the information.