You MUST remember to use Super Craig & Wonder Tweek’s individual solo power before meeting with Mr Mackey and gaining a new combined power for said buddies. I recommend playing to the point where you team up with the Freedom Pals and have access to every buddy, then immediately go pick fights and swap in buddies for each fight you have yet to use an ultimate power for. Once you have used every buddies individual power (excluding Coon), the trophy will unlock.