This is an unedited 900+ words! Yay!

Ok so Pokémon masters updated their main story today and there's a lot to unpack.
For starters, I'll just say that Paulo is actually a great representation of someone who is probably not doing very well mentally but doesn't exactly get the help they need.

Who's Paulo? Well the most forgettable rival ever... sadly.

No like seriously... hardly anyone remembers him.

Ok so... there will obviously be spoilers in this, so here's your spoiler warning.

Firstly, let's establish some backstory. Paulo is canonically your rival whom you meet while exploring a random cave (due to team break) in one of the first few chapters of the game.

As the game progresses, he notices how you (the protagonist) continues to get stronger at a rapid rate. Before long he finds himself being left behind multiple times, and unable to catch up with you.

Now Paulo is a pretty calculative person. So, he really doesn't understand how he keeps lagging behind despite all of his calculations and strategies. (This is more evident in the villain arc than the PML arc, but you could still see this trait of his in both)

So, well, he gets upset because he doesn't understand why he can't catch up... and also because he feels helpless due to how he isn't strong enough to hold his ground at times. Due to this, he starts to get obsessed with growing stronger and gaining more power (and it shows throughout the entirety of the story)

Here, take a screenshot:

Later on in the story, he gets cornered by team break, and gets saved by two other trainers (Wulfric and Vikstrom). He forms a team with these two trainers and joins the PML. During the competition, you face Paulo in the Second round of the finals. For once, he actually seems a bit more confident with facing you but eventually loses due to the plot. After you beat him, he seems visibly upset, and you're given a choice of dialogue. If you choose the one where you state that he's really strong, he gets into a battle stance and seems frustrated. My own interpretation of this (feel free to interpret it differently) is that he doesn't feel that he deserves to hear those words, and thus feels that you are either 1, pitying him, 2, mocking him or 3, overestimating his abilities. Basically he doesn't feel validated. Of course, we mean this genuinely. (Or so I think?) Either ways, he doesn't feel as though he deserves it. He then claims that he's fine, apologies for acting weird, and leaves the arena with a fake smile (as claimed by the other characters in the story).

This series of dialogue then follows when he talks to himself on the beach:

And yea... honestly I don't really know how to put it into words so... these screenshots would have to do.

After this exchange, he's hardly seen again till one of the last few chapters of the PML, where Lear claims to have gotten a bad vibe from him. (Lear is another very interesting character I may or may not touch on another day)

With the villain arc finally comes character development for Paulo, (who at this point, half of us have already forgotten exists due to Pokémon Masters' update schedule of a new chapter every 3-4 months or so)

Paulo is seen to think and reflect quite a lot about things that happen according to the first chapter of the villain arc that we've gotten today. He is also shown to have become even more withdrawn than ever, clearly hiding his feelings even more than he usually does. He spaces out quite frequently and when asked a question, comes up with a generic answer or brushes it off. He also doesn't seem to want to except help anymore:

This is probably due to him losing in the Pokémon Masters league (The PML), and he may think that he was just being a burden to his teammates... or maybe he just thinks he's relying on them too much. (Also, just saying, this part of the story kind of hurts. Not as badly as N's story at least.)

He also feels worthless, and probably sees himself as a liability.  As such, he tries to help out (a little too much), and gets rejected multiple times cause let's face it. While Paulo is technically a strong trainer on the grand scale of things, here he was running up against people like Red, Blue, Misty and Erika to help stop team rocket. Obviously, he's viewed as one of the weakest on the team, and the other more capable team members wouldn't want him to overexert himself and his rockruff.

Also while this is happening, he gets to know about Red beating half of team rocket single handedly, beats a few grunts only to realize Misty and Erika had beaten way more in that amount of time, and watches his rockruff faint and us fighting team rocket alongside red and blue. I don't even need to be him to find the entire thing extremely demoralising.

Now... that's about all I have to say at the moment. I'm honestly really interested to know how Pokémon masters would continue developing Paulo as a character. (The one they gave Lear was pretty good so I've high hopes.)

In Pokémon Sword and Shield, Hop underwent a similar development (but much milder, and his reasons are pretty different from Paulo's) and honestly, it could have been better.  As such, I'm interested in seeing how DeNA would handle such a character.

P.S: Pokémon Masters is a great game, I totally recommend getting it.