While one alone doesn’t have much power, a chain of many Tynamo can be as powerful as lightning.
– Pokemon Black Pokedex
Due to its ability of Levitate, Tynamo, and its evolutions, have no weaknesses. Unlike the two Dark/Ghost Pokemon that also have no weaknesses though, Tynamo can be hit by super effective Ground moves if its ability is taken away somehow (through Gastro Acid, Mold Breaker, Mummy, Simple Beam etc).
Perhaps due to this lack of weaknesses, Tynamo does not learn any moves by level-up or TM. It has 4 moves to start with, and does not learn any more until it evolves at level 39. Stat-wise, it’s got the most of Speed and Attack, with good Sp Attack as well. It’s actually faster than its evolutions, perhaps because it gets bigger, and therefore slower, as it evolves?