OH MY arceus IT'S MY BOI GROWLIE
As the resident Arcanine fanatic, I can absolutely tell you about naming him.
I have two. The first I got in Moon after only chaining about 23. The second I found in Go the day before my birthday, a year ago. The second one probably won't help you because right now his name is Birthday Boy.
But the first -- his original name was Aurum. You know, because sparkly yellow -> gold etc, etc. But @kibibarel you might get a good idea if you look at your Growlithe's Nature and Characteristic, like I did.
(Okay, I hate to admit it but this might be turning into less a name idea and more a personal fangirling.)
"Quirky" and "Mischievous."
And I thought, "There's only one other yellow anomaly who is quirky and mischievous that I know."
But of course, Growlithe is much too good boi to be named directly after an omnicidal Eldritch Abomination.
Hence why I decided to call him Billy. Much more innocent and playful.
And that's the start of how I ended up making not one but two Gravity Falls-themed teams in Gen VII.
Billy the shiny Arcanine is great buddies with his teammate Stanford, the shiny Espeon.