Here are the pictures of the remaining Gym Leaders that were not revealed during the pre-release trailers:
First up, the one I'm sure you all were eager to see, say hello to our first Dark-type Gym Leader in the series: Piers!
Supposedly, he is Marnie's older brother, at least that's what his bio implies (not to mention he has Team Yell's symbol on his shirt and card).
Next up, the Fairy-type Gym Leader who we knew about since the earliest leaks: Opal!
Her second trainer card shows her with Bede. Maybe they are related (possibly Bede's grandmother)?
Now for another set of Version exclusive Gym Leaders for a given town: the one on the left is Melony, the Ice-type Gym Leader. The one on the right is Gordie, the Rock-type Gym Leader.
They are mother and son respectively, and their bios talk about a complicated relationship between the two of them.
Next, say hello to the Fire-type Gym Leader who we learned his name about since the earliest leaks of the game: Kabu!
Kabu is originally from the Hoenn-region according to his bios.
And last but not certainly not least, here is the really cool-looking Dragon-type Gym Leader: Raihan!
He has a big rivalry with Leon according to his bio. He is also called "the most skilled Gym Leader in the Galar region," so he is the last Gym Leader you fight in the story.
All of the Gym Leaders also have secondary trainer cards that show other aspects to them. Here are the highlights of those cards:
Yep, Nessa is a model!
This is why I think Opal and Bede are related.
Allister without his mask!
Piers with shorter hair.
You can view all of these Gym Leaders' trainer cards and their bios in this link.
So far, I'm really liking Kabu, Piers, and Raihan from the looks of them. Character-wise, Piers may just be my favorite out of the Galar Gym Leaders so far, at least from reading his bio and the fact he is Marnie's older brother (most likely)/has some sort of affiliation with Team Yell will probably give him some prominence in the story.