Tested.
- Wigglytuffs on Route 1.
- Rhydon on Route 24.
- Tropius in Viridian Forest.
And this is when I checked "Retain Pokemon Strength..." I'm pretty sure that these guys have higher BSTs than what would be around them normally.
Also, I think that the starters should be unevolved and able to evolve. Getting something like Snorlax would turn early-game into a "click Tackle and win" situation.