Team Skills are a type of skill that most Vivosaurs have. These skills can only be used if the dino's types or diet match the other dinos on your team. For example, T-Rex would get to use his team skill if Guan and Gorgo are teamed with him; this is because they all are the same attribute with the same diet. Or, for example, Krona gets its team skills when alongside an Alio and an Elasmo, because all three are of the Water element. However, the three Japanese Vivosaurs, F-Raptor, Futabi and Mihu can only use their team skills if they are teamed with the other two; Otherwise, even if F-Raptor is teamed with two other Earth Vivosaurs, none of them can use the team skill at all. One thing to remember about Team Skills is that they never land critical hits. To use Team Skills you must get the team skill book, which is located on the 2nd floor under wool beard's room (the book is inside a chest). Then holt will come out and explain how to use them. Remember, Team Skills will show up in battle if you see a gleam on the 3 medals DURING medal selection (before the battle). Team Skills can be used with Vivosaurs in the SZ but if 1 Vivosaur is eliminated then you can't use your Team Skill anymore.
In Fossil Fighters: Champions, team skills are unlocked on Ilium Island after you battle Ted Tudor. Ted will shout at you when you enter the fighter station and you must beat him in battle before unlocking the ability to use Team Skills. Unlike the first game, team skills still can be used if one of the vivosaurs is KO'd from battle, but the Team Skills will decrease in power for every vivosaur lost. Also an improvement, many team skills have special effects, such as poison, unlike in FF, in which no Team Skills had special effects.
Check out the List of Compatible Vivosaurs.