They'll all themed after their typing. Some more obvious than others. Here's what I could figure
Kanto
* Brock: Just the word "rock" with a B added
* Misty: Mist is a water phenomenon
* Lt Surge: Surge is an electrical term
* Sabrina: Possible reference to Sabrina the Teenage Witch?
* Giovanni: Gio sounds like Geo and only has the e as different, from Geology
Johto
* Bugsy: Pretty obvious
* Morty: "Mort" is something often used in things associated with them, like mortician
* Chuck: A possible reference to Chuck Norris?
* Pryce: Rhymes with ice
Hoenn
* Roxanne: "Rox" sounds like "Rocks"
* Brawly: He's a brawler
* Wattson: Derived from watt, which is usually an electric term(like a 60 watt bulb)
* Norman: Replace the n with l
* Winoa: Her name's derived from wind
Sinnoh
* Roark: Corruption of the word "rock"
* Gardenia: Comes from garden
* Crasher Wake: Sound very similar to Crashing Wave
* Byron: Rhymes with "iron"
* Candice: She has ice in her name
* Volkner: Derived from Volt
Unova
* Chili: A spicy, hot foodstuff
* Elesa: "Ele" comes from "Electricity"
* Clay: An earthy material
* Skyla: Sky makes up most of her name
* Brycen: "Bryce" is a rhyme of "ice"
* Marlon: Derived from "marlin"
The alola captains are actually all named after plants. In other words hala, hau, kukui, mallow, etc. are all plant names. As fir violet in kalos, the only thing that comes to mind is a Violin beetle
They'll all themed after their typing. Some more obvious than others. Here's what I could figure
* Norman: Replace the n with l
Replace the second "n". He should have worded it better.Lorman? /s
Marlon: Derived from "marlin"
Sinnoh
* Roark: Corruption of the word "rock"
* Gardenia: Comes from garden
* Crasher Wake: Sound very similar to Crashing Wave
* Byron: Rhymes with "iron"
* Candice: She has ice in her name
* Volkner: Derived from Volt
Hoenn
* Roxanne: "Rox" sounds like "Rocks"
* Brawly: He's a brawler
* Wattson: Derived from watt, which is usually an electric term(like a 60 watt bulb)
* Norman: Replace the n with l
* Winoa: Her name's derived from wind
Johto
* Bugsy: Pretty obvious
* Morty: "Mort" is something often used in things associated with them, like mortician
* Chuck: A possible reference to Chuck Norris?
* Pryce: Rhymes with ice
Kanto
* Brock: Just the word "rock" with a B added
* Misty: Mist is a water phenomenon
* Lt Surge: Surge is an electrical term
* Sabrina: Possible reference to Sabrina the Teenage Witch?
* Giovanni: Gio sounds like Geo and only has the e as different, from Geology
They'll all themed after their typing. Some more obvious than others. Here's what I could figure
Kanto
* Brock: Just the word "rock" with a B added
* Misty: Mist is a water phenomenon
* Lt Surge: Surge is an electrical term
* Sabrina: Possible reference to Sabrina the Teenage Witch?
* Giovanni: Gio sounds like Geo and only has the e as different, from Geology
Johto
* Bugsy: Pretty obvious
* Morty: "Mort" is something often used in things associated with them, like mortician
* Chuck: A possible reference to Chuck Norris?
* Pryce: Rhymes with ice
Hoenn
* Roxanne: "Rox" sounds like "Rocks"
* Brawly: He's a brawler
* Wattson: Derived from watt, which is usually an electric term(like a 60 watt bulb)
* Norman: Replace the n with l
* Winoa: Her name's derived from wind
Sinnoh
* Roark: Corruption of the word "rock"
* Gardenia: Comes from garden
* Crasher Wake: Sound very similar to Crashing Wave
* Byron: Rhymes with "iron"
* Candice: She has ice in her name
* Volkner: Derived from Volt
Unova
* Chili: A spicy, hot foodstuff
* Elesa: "Ele" comes from "Electricity"
* Clay: An earthy material
* Skyla: Sky makes up most of her name
* Brycen: "Bryce" is a rhyme of "ice"
* Marlon: Derived from "marlin"
Clemont is from lemon, as lemons can be used to power light bulbs. But clemency can also refer to being lenient and towards misbehaviour, and Clemont is very patient with his little sister.
Ilima - Named for a Hawaiian island
Milo: Could come from grow, but all the translations refer to the Yarrow.
Bea: Seems to come from bean accross different translation. Also, looks like she could be kind of a beast at the gym.
Allister: Probably named after Crowley, a famous occultist. His name is japanese is literally onion because it has oni in it.
So it looks like the Galar gym leaders are named after healthy food... part of the whole lovely British countryside thing it has going on. Guess the dev team never saw a meal in a Wetherspoons.