Knuckles the Echidna was trying to train you so you could actually help him, Sonic and Tails. But he isn't used to training anyone so he's testing your agility by making you dodge boulders that he's throwing at you, he makes you punch rocks, trees and any other hard object to test your strength and he fights you to test your durability. It's impressive your still alive honestly. Right now you two are training and it's near sun down.

Knuckles the Echidna: "Fists and shoulders up. Your leaving yourself wide open for a attack. You want to be helpful and be a warrior or challenge then you need to keep going."