I legitimately caught 149 in Blue Version back in the day, before GSC. Two were missing: Primeape and Mew.
I got busy. And then, my Game Boy Pocket got damaged badly; it was the batteries, quite literally exploding in my hands, but Nintendo of America's amazing customer service told me they'd replace my GBP for free anyway, as well as fix the game that had been inside of it (the explosion had damaged multiple things. thankfully, not my fingers - they got weird acid on them but I washed it off quick before it was a problem.) Well, I got the game and GBP back, but the save wasn't recoverable. Boo.
Sometime later, after GSC had come out, I picked up Red to get more TMs from backtrading, but the game just didn't work anymore. The battery backup went kaput. So I called Nintendo up, they of course offered to replace it for free, and they asked me how far I'd gotten. I said, truthfully, I didn't remember; I had a lot of pokemon, including Mew on it at that point, but the number of gyms I was on when I'd last quit and all that, I couldn't remember at all. I got back a save with 8 Badges and 151 Pokemon. They had a bunch of funny names in their boxes.
The closest I've ever gotten since was 411 out of 493 in HG/SS, and I didn't try at all in BW/2. Too many now. Too much of pain. Just not worth it.