Gifting

No trading in Haypi because otherwise new players could transfer their startup benefits (i.e. Draco and egg spawned epics) to existing players, giving them an unfair advantage.

Pokemon doesn't have as many startup advantages, and players pretty much have to play for a decent while before they are allowed to trade. It shouldn't be too problematic for HM to do the same by setting a trade function to be unlocked at, for example's sake, level 17.

Then again the game does fine without a trade function. If anything, its absence denies real money transfers and account farmers making a profit from the game.

From my experience, any MMO game that has a trade function leads it to automatically become an RMT magnet. I rather not have trade so I don't have to deal with/compete with RMTs.