Fusion
This information is from: Anime
The Dance
Goku learned this during the five years of
inactivity between the end of the Cell Game
and before Gohan started school at Orange Star
High School. As the name suggests, the major
requirement for this type of fusion is to have the
two people involved in the fusion perform a dance,
the two people also have to have the same power level
( which is not hard because Dragonball Z Fighters can lower
there powere levels) which are mirror images of each
other, resulting in a new warrior, who has the attributes
of the two warriors who formed the new one. When performed
successfully, the newly formed warrior will be significantly
stronger. This type of fussion will last for a half an
hour, I the Dragonball Z episode were Gotenks is formed
it takes Trunks and Goten Three trys to get it right.
Potara Earrings
The fusion technique of choice
for Kaioushins which time forgot, this technique
is allegedly hundreds of times better than the
Dance Fusion. For fusion to happen, two people only
need to wear the ear-rings of a Kaioushin. (Note
that while this fusion was supposed to have been
permanent, its properties seem to wear off under
unexpected conditions, like being inside the body
of a magical being...)