According to a well known Nintendo insider, Super Mario. Bros. Wonder on Nintendo Switch is “hard” and “absolutely decimating testers.” The report comes the way of Zippo, who notes that “if you think this game is going to be a walk in the park, then you’re in for a rude awakening.”
Given Nintendo’s history, there will almost surely be assist options or other ways to make the game more accessible. Nintendo tries to cast a wide net, especially with Mario games.