I know this makes me a pedantic fuckwad, but...
This is wrong, I hate myself for knowing why it's wrong, so understand that saying this brings me no pleasure. Fuck this gay earth, here goes.
When the Cell saga ended, the known SSJ transformation hierarchy was as follows:
SSJ1 -
OG spikey gold hair. The form
Goku achieved to defeat Freezer-domo.
Not enough to beat an Android 18.
SSJ1 Stage 2 - AKA "Ascended Saiyan" - The form Vegeta and Trunks achieve
in the time chamber. An improvement over form 1
in every measurable way; Vegeta and Trunks use this to
beat the snot out of Semi-Perfect Cell. Enough strength to damage but
not vanquish Perfect Cell.
SSJ1 Stage 3 - The stronger, bulkier form that
Trunks uses for holding hands. Cell chastises Trunks for not realizing this form slows him down considerably. Goku and Vegeta
had also attained this form but consciously chose not to utilize it due to its glaring weakness.
SSJ2 -
The new plateau,
faster than Stage 2 and stronger than Stage 3. Gohan was the only one to achieve this form by saga's end. In last week's DBS, seeing that Gohan had thrown this all away and become a family man in the immediate wake of losing everything he ever loved probably made Trunks
want to become the ultimate an hero of our time.
So, even after spending a 2nd year in the time chamber, Trunks could only manage bulking up to Stage 3, so he wisely chose to further hone Stage 2.
Shortly after Gohan defeats Perfect Cell, Trunks returns to his timeline and immediately dispatches Androids 17 & 18, then a
hapless Imperfect Cell 3 years thereafter -- all in Stage 2.
Therefore, when Goku commented two episodes ago how impressed he was that Future Trunks had
obtained SSJ2 and slain Dabura and Babidi of his own accord in the lost years, it was a "reveal" of Trunks' progress after we last saw him blast Future Imperfect Cell as Stage 2 in 1993.
Edit: Am disgusted with myself.