Synonyms that are in the dictionary are marked in green. Synonyms that are not in the dictionary are marked in red.
Antonyms that are in the dictionary are marked in green. Antonyms that are not in the dictionary are marked in red.
Goku's inability to ever turn to the Kaio-Ken Attack again after he becomes a Super Saiyan led to the belief that these two transformations can't be used in tandem.
Source: https://www.cbr.com/dragon-ball-details-confusing-because-of-super/