"Trading among trainers in the pokémon world is all well and good, but it has its limits. Trading machines really only excel at one type of trade, the one pokémon for one pokémon trade. Beyond that people have to get a little creative. That's where we come in. We couriers are commissioned by people looking for a specific pokémon or object, usually something rare, to find someone with that object and strike up a deal that benefits both. Generally we earn a fee for each trade depending on the complexity, a portion of which may consist of items that will be useful for the couriers journey or that can be traded to others that are seeking them. And that's just the direct benefits."

The pokémon courier service is effectively a quest hub that can easily be placed anywhere from some to every major city, each containing several singular quests or short quest chains with interesting benefits. The big perk of having such a place from a design standpoint, is to have all your generic fetch quests in a single, yet distributed, place for ease of pick up and turn in, as well as making more room in other hubs for

A singular or starter quest could be a simple commission. A new (NPC, although maybe new PC's may be able to take advantage of this) trainer has requested a specific pokémon from their [authority that gives out starter pokémon]. You accept the quest to go where this pokémon is found and find a suitable partner for a new trainer. Mechanically, any time you are in an area where this pokémon is found you have an X% chance to find a lvl5 pokémon of the species in question that you can't run from. Succeed in capturing it, take it to the commissioner, return to any courier-house, and quest complete. Dead simple. Reward: A moderate amount of poké-cash, 2-3 replacement balls of the type you used to capture the pokémon and maybe an antidote two if it say had a poisoning attack or something, and a chunk of trainer-EXP, repayment of resources and cash for the time spent basically. The real reward is the EXP, like most quests.

Let's turn it into a quest chain then. When you deliver the pokémon to the new trainer they tell you about a friend of theirs that is dissatisfied with their new partner, and that they are looking for a partner that would be more suited to the contest circuit than that just wants to get stronger. But they care enough about their pokémon that they don't just want to release them and find them a new home with someone more suitable. Let's add a twist, their not looking for a specific species of pokémon, just a general type, say for instance, a flying type. You accept the commission fee and Yanma from the friend, then not knowing where to look next you go to the nearest courier-house to ask and turn in the last quest for its commission.

The courier in charge there checks their database (a simple explanation for how they seem to know everybody) and finds a suitable Swablu up for trade and gives you a location to inquire about it at. Go and talk to the NPC trainer and...oh wait you just talked to an NPC trainer. Battle-larity ensues, and oh look a suitable level Swablu is on their team, but they're not interested in Yanma. But one of their friends who is looking to be a bug-type gym leader has a female Combee they've been considering trading for for some time now, but have never had a suitable pokémon for. They call their trading friend and set it up for you. Complete both trades and you get a commission from the Swablus original trainer trainer and from Yanma's original trainer, as well as a chunk of trainer-EXP (As always the real reward of questing)

Details can become important in these quests as well, consider the female Combee. Where did the original trainer get it? They're quite rare. A later quest could very well have someone looking for one, and you go ask the trainer from the last quest, which at this point could be several quests in the chain ago, to ask them where they found it. They challenge you to a battle for the information (and you find a Yanmega on their team), after which they tell you about the Combee Hives honey farm out in an obscure corner of the world (honestly who wants to live next to a beehive, let alone a pokémon beehive). Going there the owner tells you that having too many Vespiqueen in too small an area causes the hives to swarm, a dangerous proposition to be sure, so is always looking to sell female Combee before they evolve. Oh look, now you have a place where you can buy female Combee for evolving your own Vespiqueen. So much easier than hatching hundreds of combee eggs to get a female, let alone a female with good IV's.

This post is getting too long, but the premise holds. I invite others to take this idea and run with it, adding their own twists to the basic fetch quest both to make them suitable to the pokémon world, and make them interesting again.