Here's the simplest scenario (no matter how out of scale it may be) I can provide that will help highlight issues behind this. This spectacle happened years ago at PC. It honestly destroyed the trade market (so don't think this is make-believe or that Pokemon is just a kid's game!):
1. OT trades Client their Shiny flawless Palkia for a shiny flawless Rayquaza.
2. Client decides to giveaway Shiny flawless Palkia + more.
3. OT cannot control what happens to their Pokemon once trading it, true, but OT genuinely believed that Client would uphold a duty to fairly distribute the Pokemon, not freely distribute.
4. OT's business begins to decline because no one would trade him for the shiny flawless Pokemon; customers can get it from the giveaway thread (customers are free riding).
5. OT does not want to RNG abuse anymore because their Pokemon ended up as "valueless" and in a sense, OT cannot make a profit. OT is wasting their time (RNG takes time to learn and perform).
6. If there are less RNG abusers, how do you suppose future shiny flawless Pokemon enter the market? Via Pokesav and Pokegen, most likely.
7. If I'm not to the protect the most basic rights of the OTs, then yeah I suspect that RNG abusers become more scarce
If OT gave permission and/or wanted to make it a public Pokemon, then that's that. Their Pokemon is very cheap to get and they didn't want anything in return in the first place.
You'll just have to go around asking for the owner's permission. Some OTs really don't like their Pokemon being free because they want to profit, stay in business, stay interested in playing, etc. Some don't care.
All of this wouldn't be such a shock if you reviewed the giveaway rules in the sticky, lol.
I imagine there's also a whole other level with event Pokemon and devaluing.. ugh... (for one, you can't prove who is the OT). I wonder how many times someone obtained a super rare event only to mass give it away, basically saying a big screw you to all those who traded an arm and leg for a copy. There's soo much underlying psychology and even business elements in Pokemon trading. It's fascinating, right ?
You can offer others OT if you trade something of fair value in return... You can offer your OT for anything, like a patrat.
Also, I said you can only have 1 active thread at a time. Either have a shop, a shop with a giveaway in the post, or a giveaway. You can't have both an active shop and a giveaway (2 separate threads). There is a 1 open thread per person rule. xD