Can I create a custom character in Pokemon Go for my business?

My boss wants to create custom Pokemon that represents our business mascot in Pokemon Go to drive more revenue. Is this even possible?

No. The game does not offer such a feature, and the game's owners have not advertised that kind of partnership service.

It is almost certainly not something they would do, even if paid a lot of money for the privilege—The Pokémon Company's brand is heavily dependent on the list of characters, and adding new ones that promote other companies' brands or characters would massively damage their only asset.

One possible way to use Pokemon Go for marketing could be to create a player character whose name is an advertising slogan, such as "EatAtJoes", "ShopValuSave", "ValleyTractorFarmSupply", or "PJCertifiedConsultants". You could then go around, take over gyms, and put your own Pokemon in them, which will result in your character's name being shown to others visiting the gym.

Before doing this, you should have a corporate attorney review the Pokemon Go TOS to make sure that this is not disallowed.

Added years later:

Niantic now has a Pokestop sponsorship program, in which companies may pay to have their own branded Pokestop or Gym in the game. These stops contain a branded image, a branded name, and an advertising blurb in place of the regular location description. Starbucks (coffee shop chain) has been a major sponsor in many areas around the USA, and Sprint (the mobile phone company) formerly had locations but seems to have pulled out in many (or even all) areas.

While most of the sponsored locations I have seen seem to belong to major chains rather than small businesses, there's no reason that you couldn't contact Niantic and ask about the possibility of getting one or two stops for Joe's Diner, Valley Tractor Farm Supply ("Come test drive the new 2021 model combines!"), or PJ Certified Consultants ("Maplevale's favorite accountancy firm since 1981!").

I have no affiliation with TechCrunch or Niantic.

Unfortunately this isn't possible to do.

You can only ever create a character that would walk around (which is very limited in cosmetic choices)

However Pokemon are put in as designed from their games and wouldn't have any customs made.