

Grounder accidentally puts a "genius chip" in his head and it makes him so smart that he easily captures Sonic and even takes over Robotnik's operations.
Sonic frees a prisoner who has been locked at Robotnik's Fortress for 30 years who wants to find his long lost girlfriend which Robotnik also loves.
Robotnik creates a robot fox family when he finds out that Sonic is trying to find Tails a new home to keep him safe.
Robotnik buys new gadgets from an enterprising salesman to help Scratch and Grounder catch Sonic, but winds up regretting his purchases when they keep backfiring.