When you want to learn some attacks, seek out a master. It takes two training sessions with your master to learn one attack/ability. There are benefits to training with a master. The master will have a limit to how many people he/she can train at one time.Depending on the master, you may get an extra increase in PL.
Master Roshi-The infamous turtle hermit.
Korin-Mysterious cat that grows the senzu beans.
Dende-Guardian of Earth
Roshi(0/2) Lightening Flash Surprise Attack, Kamehame, and Super Kamehame 100+PL
Korin(0/2) Zanzoken and Sense 50+PL
Dende(0/1) Namekian Limb Extentsion 150+PL
Guru-Spiritual leader to the Nameks.
Guru(0/2) Namekian Limb Regernation, Kyodaika, and Gekiretsukodan 150+PL
King Vegeta-King of all Saiyans.
King Vegeta(0/1) Final End 200+PL
Unknown-Leader of the Yardratts
Unknown(0/3) Instant Transmission 0+PL
King Kai-Guardian of the North Galaxy
Grand Kai-A higher level Guardian
Supreme Kai-Ruler of all the Kai's
Elder Kai-An old Kai who has the ability to release the potential in warriors.
Jenemba-Ruler of Hell
King Kai(0/5) Spirit Bomb and Kaio Ken 1000+PL
Grand Kai(0/4) Dragon Fist 1500+PL
Supreme Kai(0/2) Potarra Earrings 500+PL
Elder Kai(0/1) Releases full Potential 0+PL
Jenemba(0/4) Nothing 2000+PL