I know Goku can do it because he did it in the otherworld tornament but Krillen can do it to in Dragonball he did it while fighting Chozu the the world martial arts tournament. Krillen started to charge kamahamaha while Chozu was charging dodonpa when chozu fired Krillen teleported next to Chozu and fired. So maybe it is a power of the kama because it is so flexable or it is a move that master Roshi new and taught them. So maybe Krillen should have it as well.