I think we're being a little too harsh with the definition of an eSport. As others had mentioned, it basically already is an eSport because of VGC, but I will get more to my definition of an eSport later.
Altissimo had mentioned that the game in question has to be easily understood to be a (perhaps successful) eSport. However, I don't really agree with that sentiment because I have seen stuff like League of Legends and CS:GO on TV and I don't understand really anything about those games yet I find CS:GO to still be somewhat entertaining to watch. (sidenote: I still can't believe video games are being shown on TV lol wut)
Now I believe an eSport can be pretty much anything as long as it is "watchable" as others have also mentioned, but in today's world this pretty much includes every video game imaginable. I mean, take a look at how many people watch games being played on Twitch or even how fervently people follow tournaments on Smogon/PS. Now I agree Pokemon and other turn-based games can have a watchability problem, but I wouldn't think it would be that extreme.
Worldie mentioned that pokemon has no flashy plays but I think there are exciting moments even if they aren't obvious to the non-pokemon player. Critical hits, unique or niche strategies being unleashed or even double switching to change momentum can be exciting for the pokemon fan watching. I know the goal is to garner as many viewers as possible (i.e. expand the brand), but again I go back to my example of CS:GO and League of Legends. I know nothing about those games but can still grasp the occasional exciting moment, especially based on how the crowd, competing players, announcers, etc react. Announcers, more than others, can play a large role in these events, helping unknowledgeable viewers learn the basics of the game, at the very least, so they could explain pivotal moments in the match, key concepts, strategies, etc, so I don't believe watchability would be that large a problem.
In conclusion, I think
Rapti said it best; this is less a question of
is Pokemon an eSport? and more of
is / how can Pokemon be a popular eSport? With so many games having a large following on Twitch, Pokemon's large Smogon/PS following, and official VGC events already taking place, it definitely is an eSport. Chess has a following and sanctioned championship events with prize money, which I think is the most direct connection to Pokemon / other turn-based games having possible
success as an eSport