it has been stated in other threads - there is no "OT Alpha Dex", the caught OT is linked to having caught the normal form OT. to complete the alpha dex you can buy or trade alpha starters.
they will never appear again, not in their baseform or any other evo. Players who want to complete their Alpha dex will have to buy or rent them, they can resell them right after anyways, so its not like they have to make a loss for it. "caught OT" in Alphadex is also archieved by catching the non alpha form afaik.
i think you can do reasonable profit with a main alone too, let it just be regular good payout npc. there are points for both sides, i just think the term "scam" is a bit over the top
When you consider the time you need to breed and level the mons you could probably do a couple of gymruns in the meantime which would provide much higher return - so describing bought ready ones from gtl as a scam is highly questionable
Even considering a leaderboard is ridiculously silly, its so easy to manipulate that it wouldnt even hold any value. "Hey buddy, i want to be on the leaderboard for a while, can i hold your money for a week?"
The 2b limit isnt just a random number, it has to do which maximum number can be displayed in java without breaking the game, which is 2147483647.
https://runestone.academy/ns/books/published/apcsareview/VariableBasics/minAndMax.html
So i doubt this will ever happen.