Proposition in on at

Take out "the most" and you're good.

What if I take only the “most”? Like this:

“João Lima is a communication designer and art director who works on a freelance basis in the various disciplines of visual design.”

Is it incorrect?

And if I take only the “most”? Like this:

“João Lima is a communication designer and art director who works on a freelance basis in the various disciplines of visual design.”

Is it incorrect?

You could say that. That means the person works in all of the various disciplines.

Adding the makes it definite. Without the it's indefinite.

Thank you!

And what about this?

“Born in Viana do Castelo, Portugal, João Lima graduated in Communication Design by Oporto's Superior School of Art and Design in 2009.

He started in this business by doing internships at the award winning studios R2 and White Studio. Then he worked two years as a Junior Graphic Designer at the great Studio Andrew Howard. In 2012 he began working on a freelance basis (between Oporto and Madrid) for his own clients while also kept occasionally collaborating with other graphic design studios like, among others, the Oporto based Studio Dobra.”

It's mostly good. The only thing you really need to fix is "kept." Either take it out or change "while" to "and." I'd also take out "among others." It's implied that Oporto based Studio Dobra is among others.

And something like this?

“He started in this business by doing internships at the award winning studios R2 and White Studio. Then he worked two years as a Junior Graphic Designer at the great Studio Andrew Howard. In 2012 he began working on a freelance basis (between Oporto and Madrid) for his own clients while keeps occasional collaborations with other independent graphic design studios like, among others, Studio Dobra.”

Mebbe Jo you could delete the "the" too

Edited to remark see also Loner #....054

It's wrong. Any verb used immediately after "while" has to be gerund (end in -ing).

...while occasionally collaborating with...
...while having occasional collaborations with...
...while continuing to occasionally collaborate with...

Any of those work. My preference is the first. Keep is an odd verb to use in this scenario.

Like this?

He started in this business by doing internships at the award winning studios R2 and White Studio. Then he worked two years as a Junior Graphic Designer at the great Studio Andrew Howard. In 2012 he began working on a freelance basis (between Oporto and Madrid) for his own clients, while occasionally collaborating with other graphic design studios like, among others, Studio Dobra.

That's fine.

It's perfect Jo