Simplify the following text for a Grade 5 native English-speaking person.
Original: In other Sonic titles , he has been seen away from the Master Emerald at times , such as in Sonic Heroes , where Knuckles joins forces with Sonic and Tails , becoming the power member of Team Sonic .
Simplified: He is very aggressive and does not like Sonic very much . He first appears in the game Sonic & Knuckles .