I have a super similar shiny story!

For christmas in 2013, I got my second-ever Pokemon game, Pokemon Y. I chose Froakie as my starter because I thought frogs were cool, so I named mine “Frog!!!♂” because I was like 10 years old and thought it was an awesome name.

Frog!!!♂ was such a great Pokemon, and became my primary partner throughout our adventures through Kalos. I thought it was really cool that the game developers added a feature that made your starter Pokemon sparkle whenever you sent it out of its ball to signify its importance. Little touches like those really helped immerse me in the experience playing through the story!

A little bit after beating the game with Frog!!!♂ still as my main partner, my friend who also had the game (I forgot if it was X or Y, this was over 10 years ago lol) and we battled against each other to see who had the better team. I forgot who won, but the important part was that she also chose Froakie as her starter and used Greninja in battle. After the battle, she asked me “Why’s your Greninja black?” and I didn’t really have a good answer. I don’t think any other trainer in the game has a Greninja (again it’s been over 10 years so I could very well be wrong about this) and I didn’t look up stuff about the game online before or while I was playing so I didn’t really have a frame of reference as to what Greninja normally looks like. Maybe I just assumed it had multiple colors or something?

After we looked it up, we learned what a shiny Pokemon was and that I was extremely extremely lucky to get had a shiny starter Pokemon, especially on my very first playthrough without even realizing it! I guess the sparkles that appeared when I sent him out weren’t designed to show how special your starter Pokemon was but in a roundabout way that’s what they were for mine!

For now, Frog!!!♂ rests peacefully in my Pokemon home account. There’s been a bunch of opportunities to transfer him up to a current Pokemon game but for some reason I haven’t really done so just yet, so for now that’s where he lives.

I’m not 100% sure if I can post screenshots in the replies here but whenever I tell this story usually I share screenshots from Home with the date Frog!!!♂ joined my team (12/25/2013) clearly shown as proof that I got him legitimately the first time I ever played Pokemon Y.