After the cinematic on the tutorial level, walk into the first room. After speaking with Ratchet and Air Raid, turn right. You will find three computer monitors along the wall. Walk up to the one in the middle and you will have a conversation with a person named Kup.
Unlock the following bosses by defeating them in the corresponding stage:
BOSS - STAGE Air Raid (Autobot) - Defeat him in Streets stage #6 (Arena stage #18). Barricade (Decepticon) - Defeat him in Stadium stage #6 (Arena stage #6). Breakdown (Decepticon) - Defeat him in Dam stage #6 (Arena stage #24). Cyclonus (Decepticon) - Defeat him in Streets stage #6 (Arena stage #18). Grimlock (Autobot) - Defeat him in Purification stage #6 (Arena stage #30). Hot Rod (Autobot) - Defeat him in Dam stage #6 (Arena stage #24). Jazz (Autobot) - Defeat him in Stadium stage #6 (Arena stage #6). Motormaster (Decepticon) - Defeat him in Sewers stage #6 (Arena stage #12). Shockwave (Decepticon) - Defeat him in Purification stage #6 (Arena stage #30). Ultra Magnus (Autobot) - Defeat him in Sewers stage #6 (Arena stage #12).
