Regular Wolf is the only wolf that can be used when not playing Wolf Conquest or EX-Conquest.

Berserker Wolf and Smart Wolf are the first wolves to require purchase.  They can be purchased in the Shop under the EX-Item category.  Once you bought them you can use shift to select them in Wolf Conquest or EX-Conquest modes.

Ghost Wolf will stay invisible while hanging on a wall.

Smart Wolf has the ability to "Steal" HP.  You will gain small amounts of extra shield by attacking others for a max of up to 299.

Berserker Wolf has the ability to preform a suicide kill, he will fire a laser straight forward killing himself in the process and anyone in the way.  This method is very useful against turrets.

Ice Wolf has the ability to throw an "Ice Ball".  It functions similar to a grenade any one hit will be frozen and will move slow for a few seconds.

Psycho Wolf's special ability features the same type as Ice Wolf however someone hit by the ball will be pulled towards the user.

Generally if you play with a wolf you are sure to come into contact with some people who think that the wolf is "noob".  This is usually if you are killing them and they catch hurt feelings because they cannot kill wolves as easily as humans.  You will have to ignore these users because they are ignorant to the fact that the game is called "WolfTeam".  Recently most of their annoyance is at "Smart Wolf" users, but before that they were directed at the "Guardian Wolf" users.  These people also generally like to stay and complain every time they get killed rather than leave and find a different room, but sometimes if you ignore them and kill them enough times they will leave or stop being childish every time they get killed.