To each their own, I suppose. In my opinion, I can't help but think of them as a couple, especially due to one of the scenes after the battle between the two of them in the Silver Conference. (You know, the sweet one where they share a moment alone out by the lake.) That may just be a friendship thing to you, but to me, it screams romance. Not to mention there's other bits as well that got me thinking about Palletshipping (how Ash held Gary in "Battle of the Badge," how the two of them kept their halves of the PokeBall, the idea of their rivalry just being a defense against their true feelings -- the same argument Pokeshippers use in reference to Ash and Misty's quarrels, mind you -- et cetera, et cetera).
Of course, most 'ships in the Pokemon fandom are merely supported by fan speculation and analysis with bias. (In other words, fans have the tendency to watch each episode closely to find the littlest detail that could possibly be used as proof and proclaim the pairing as "obvious" afterwards.) Palletshipping is definitely not an exception, so even fans of it may just be picking out details that they only think is proof (just like what happens with the fans of most other 'ships).