I remember having a pretty strong team in my original FireRed playthrough. The reason being that I got stuck for months and months trying to find the key to the Cinnabar gym, so I got plenty of time to train my team. The weakest member of my team by the time I reached the pokémon league was an Aerodactyl lv 56, the strongest was my Charizard (lv 70 by the time I reached Saffron City, and probably around lv 80-85 by the time I reached the pokémon league), and I also had a Dragonite. Can't remember the rest, but I probably had 1 or 2 legendary birds and maybe a Gyarados.
It all got destroyed when a friend deleted the save file and thus hundreds of hours of work...
In Sapphire I remember doing various playthroughs and picking Treecko and Torchic, but that's all I can remember. My Sapphire game has a pretty sad story as well, because I gave it to my sister when I got Emerald (because I thought Emerald was the same game but better, which I guess is true, but looking back I feel so dumb for not having kept Sapphire! xD) and she ended up losing it in some supermarket a year or 2 after...
In Emerald I remember playing with all the 3 starters (in different playthroughs, not the same one), and Rayquaza was the first pokémon I ever got to lv 100 (it should've been the Charizard of my original FireRed playthrough, though, I got it to lv 92-93 before the file got deleted). I also remember having a Wailord in the team at some point.
More recently, I'm pretty proud of my current FireRed team. These bad boys won me the second (and harder) round at the Elite Four:
- Heracross lv 54
- Tyranitar lv 58
- Dragonite lv 60
- Lapras lv 60
- Rapidash lv 60
- Venusaur lv 62
My Emerald team isn't too bad either:
- Gardevoir lv 40
- Camerupt lv 40
- Manectric lv 42
- Metagross lv 45
- Salamence lv 52
- Swampert lv 63