There are several secrets and hidden challenges in Mario + Rabbids: Sparks of Hope, such as a hidden skill tree.
Mario + Rabbids Sparks of Hope review
Terra Flora Tutorial (Spoilers ahead!)
How To Earn Skill Prisms Mario + Rabbids Sparks of Hope|Game8
All Main Missions In Pristine Peaks In Mario + Rabbids: Sparks of Hope
Mario + Rabbids Kingdom Battle' Adds Free Competitive Mode
Mario + Rabbids Sparks of Hope Review - An Adventure Worth Raving About
Mario + Rabbids Sparks Of Hope Guides
Mario + Rabbids Sparks of Hope - A Truly Ginormous Goomba Walkthrough - Neoseeker
Review: Mario + Rabbids Sparks of Hope
XPG-Grit
Bury the Hatchet Quest Guide and Walkthrough
Off-Color Quest Guide and Walkthrough Mario + Rabbids Sparks of Hope|Game8
Mario + Rabbids Sparks Of Hope Guides
How To Unlock The 5th Skill Tree In Mario + Rabbids Sparks Of Hope
Mario + Rabbids Sparks of Hope - How to Unlock the Sparks Skill Tree - SAMURAI GAMERS