Transformations

Transformations became an important part of the Dragonball Z universe once it reached the Frieza Saga. Transforming allows a person to do incredible things -- usually increasing his or her Power level, which in turns increases the stats the Transformation governs over. Of course, while Transformed, you cannot charge beyond the PL when you first transformed.

Saiya-jin
Saiya-jins have decent Transformations stages, each increasing his or her Power Level to a good extent. Of course, this power can only last as long as the Saiya-jin has enough strength to keep up his ascended state. Once your Power Level drops below the requirement of the Transformation, you revert.
Name	Affects	Drain	Multiple	Requirements
Giji Super Saiya-jin	Ft,Sp,Po	None	1.5*	Base Power Level of at least 2,000
				Base Power of of at least 50.
Super Saiya-jin	All	None	2.5	Base Power Level of at least 5,000
				Base Power of of at least 50.
Ultra Super Saiya-jin	Bo,Ft,Po	Sp*	7.5	Base Power Level of at least 7,500
				Base Power of of at least 100.
				Base Speed is reduced by 50%
Super Saiya-jin 2	All	PL	5	Base Power Level of at least 10,000
				Base Power of of at least 100.
				Lose 10% Max PL per round

Changeling
Changelings have a different approach to their transformations. Instead of their transformations increasing their maximum Power Levels, the transformations actually allow Changelings to unlock their powers to reach their true potentials. Along with opening up their Power Level, changing also gives them changes to their body in the form of stronger Armor, Tails, Horns and nameless other things -- which is used with Body Points (BP).
Form	Affects	BP	Unlocked	Requirements
First Form	None	3	20% PL	None
Second Form	PL	4	40% PL	1 Turn
Third Form	PL	5	70% PL	Two Turns
Final Form	PL	6	100% PL	Three Turns
True Form	PL	8	200% PL	Two Turns
				"Unlocked Secrets" specialty.