So today I'm publishing this just to show you which companion can be promoted (but for some of the companions I am not sure).I'm also gonna tell you what can they be promoted into

• Here is the list 
• Bonnie Anne - Can be promoted for only 2 times. Fox Musketeer into Fox Sharpshooter into Fox Sniper
• Rat Beard - Can be promoted only 1 time.Rat Officer into Rat Commander

The Companion List
(TCL)

• Here's the list
• 1-3 companions
• Egg Shen (Duck Student) - Privateer 
• Kan Po (Goat Student) - Witchdoctor
• Kobe (Bull Ronin) - Buccaneer     
• A Crane Student - Musketeer
• Subodai (Horse Barbarian) - Swashbuckler

• Bonnie Anne (Fox Musketeer) - Available for every class
• Ensign Otter (Dog Musketeer) - Privateer
• Water mole - Witchdoctor
• Barnabas (Sloth Guardsman) - Buccaneer
• Crab Musketeer - Musketeer
• Sarah Steele (Mouse Fencer) - Swashbuckler
• 4-6 companions
• There is a difference between the 3rd and the 4th is that the 4th companion will be based on how your parents died
• Storm - Milo Graytail
• Mutiny - Dead Mike
• Shipwrecked - Lucky Jack Russel
• Giant Squid - Crab Thug
• Armada - Gaspard De Vole
• Old Scratch (Skeleton Witchdoctor) - Available for every class
• Rat Beard (Rat Officer) - Available for every class