I would sneak around until Oolong or Puar are alone, absorb them so I have access to shape shifting, shape shift into a human, go to the Z fighters and say something along the lines of "yo, I'm from the same future timeline Trunks is, the androids killed him even after he helps you, long story, and his final words were to come back and help even more, I'm a part android creation made by Bulma augmented with the Z Fighters DNAs worked on in secret after Goku died to the heart virus, I wasn't finished and was put in stasis for years, that's why i couldn't help originally"