Were Vegeta and Trunks....

[Southern Gothic]

MSSJ during the Cell Games, or did they stick with the ASSJ Forms? I always assumed ASSJ, but I hear others insist on MSSJ.

How did you reach this conclusion?

 

[Six Trails]

They definitely weren't using Grade 2. Whether or not they were FPSSs is more up for debate, though I just usually go with them being semi-FPSSs or something along those lines. I don't think they had the form fully mastered like Goku and Gohan.

 

[Fantastische Hure]

I'm not sure about them mastering Super-Saiyan. Maybe they were in the process, but didn't fully get it done until after the Cell-Games, but I think they were normal Super-Saiyans, not Grade-II or Grade-II.

 

[withheldforprivacy]

Them being bulky at Cell Games in the anime was a drawing mistake, otherwise Future Vegeta should also
be Grade 2 against Future Seventeen.

 

[Zippy]

If AT was trying to suggest they were MSSJS like Goku and Gohan im pretty sure he would've kept them in ssj form beforehand unlike having them go ssj when they had to fight (cell juniors), they dont have that G2 body imo.

 

[Papasmurf]

They were using regular Super Saiyan. I reckon they were reasonably close to mastery, since Vegeta remained in Super Saiyan form until after Cell and Goku were warped to the Kaio planet, but weren't quite fully FPSSJ yet.

 

[Let's Go Fearless!]

They seems to be close mastering SSJ but not there yet.

 

[Pyro]

The general consensus is that they were close to mastering the form, but weren't quite there yet (which doesn't explain Trunks having the same aura as Goku when he goes back to kill Cell, but whatever). They definitely weren't using Grade 2.

 

[Southern Gothic]

So they basically were stuck somewhere in between SSJ, SSJG2, and MSSJ. I agree it's likely they just trained up the SSJ form.