Its better use the short version of Super Saiyan-Jin like SSJ, SSJ 2 etc.
And about Vegeta, i suggest use Vegeta and Super Vegeta when he is SSJ.
About Goku, you can use his original name: Son Goku.
Ex:
Son Goku
Son Goku (SSJ)
Son Goku (SSJ2)
Vegeta
Super Vegeta
Son Gohan
Son Gohan...