Well, I remember back in the day when I was a little kid and Platinum wasn't even out yet, I always picked the grass starter and would play through the games randomly, stopping anywhere from the 1st to 7th gym usually. Then one day, I had an interesting idea and picked Mudkip in Sapphire. I never looked back. And Infernape became my new fav 4th gen starter.
My first diamond team was Torterra, Staraptor, Floatzel, Glaceon, Gliscor, and Dialga. (I was like 8 or so and still used legends and named myself all caps like a noob). One member I eventually replaced was Pachirisu, which I gave the exp share to in the beginning of the game and never took it off, so by the third gym it was level 40 and op. Don't know why I ever replaced it.
Also I once solo runned fire red up until the 3 islands with just Blastoise. To this day, I still have no idea how I did it. I NEVER grinded in any game as a kid. If I couldn't beat someone, I'd move my team around or equip different armor in an rpg, etc. Good times.