Transform is a status Normal-type move.
Transform allows the user to transform into the target, copying its moves as well as it's stat changes (increased/decreased Attack, Evasion, Accuracy, etc.)
Transform will fail (visually) if used against Gamma Urayne since no back sprite for the Pokemon exists.
For example, if a Duplicat that had transformed into a Cocancer uses Grass Knot against it, it will have base power of 120. However, if that same Cocancer were to use Grass Knot against the Transformed Duplicat, it will only have a base power of 20 due to Duplicat's weight.
Although Transform is supposed to also copy the opposing Pokemon's ability, the user of the move will keep their original ability. (Currently only confirmed when the a player's Duplicat uses the move with Prankster. Whether opposing Pokemon using Transform retain their abilities, or if the issue is confined to certain Pokemon/Abilities has not been fully tested yet.)
Pokémon that learn Transform
By leveling up