Is it 3v3 or solo character?
You can play which ever team size you like regardless of what your opponent chooses.
Oh really? How does that balance? Isn’t one person severely hindered?
A single character does more damage and takes less damage than a 2 or 3 person team. More details can be found here.
In exchange for these damage bonuses, the 2 and 3 person teams get assists and can cancel their supers into each other.
Solo characters get motre damage and more health to make up for their lack of assists, dhc’s, etc. Some characters are believed to do well alone, some not asmuch. There have been people who win tournaments or at least place well with a solo character. In the end it is a matter of preference.
Just by reading your link, I still have a few doubts. Wouldn’t the lack of the ensemble/duo/trio moves hurt a lone character?
The game was made so that the different options have pros and cons. Whether one team size is better than another is up to the players and what they cone up with, not tournament organizers.
Yes, it hurts… However if you look and listen to what the poster above you said, you will find all the answers:
Some characters are believed to fare well at solo or atleast arent super handicapped… Those 2 characters are ms fortune and filia.
Other characters seen to be at least decent at solo are the rest minus painwheel or val with neither having particularly good reversals.
Teams ARE better right now but as technology develops that could become less true for a multitude of reasons that im sure none of us want to go in depth on right now since weve done it all before and the jury is still out.
Take this away from this discussion:
All character/team/ratio formats are viable in tournie and probably always will be.
If that’s what you come up with, simply play a duo/trio. If someone else plays what you believe to be “low tier”, be happy 
You can play any format, all have strengths and weaknesses to balance them out. Just don’t limit anybody to playing a specific way.
It’s all preference.