1st-level Warrior feature
The sidekick gains proficiency in one saving throw of your choice: Strength, Dexterity, or Constitution.
In addition, the sidekick gains proficiency in two skills of your choice from the following list: Acrobatics, Animal Handling, Athletics, Intimidation, Nature, Perception, and Survival.
The sidekick gains proficiency with all armor, and if it is a humanoid or has a simple or martial weapon in its stat block, it gains proficiency with shields and all simple and martial weapons.