>>45848138>Latias is a Pokemon so her kiss doesn't count as romanticDude, the whole point of the Latias kiss scene was that deep down in her heart, Latias wants to be a real human girl but she's bound by her duty as the city protector.
Imagine that in the entire Pokemon Heroes movie she never transformed into a human and would always appear as a Pokemon from the beginning. In that case, all of her interactions with Ash would be completely different since he would view her more like a Pokemon rather than a human girl, he wouldn't hang out with her at the swings the way he did or talk to her like he would to a human. It's because Latias explicitly showed herself to Ash as a human first and cemented that impression in his mind that when she revealed her true nature to Ash, he still subconsciously viewed her as the human "girl" she was trying to present herself as.
In the kiss scene, she could have just flown up to the boat in Pokemon form when Ash and his friends got far enough from the city but she deliberately chose to run up in human form and present a drawing. It all comes together when you think about it. This is probably one of the few times when a topic like this was subtly addressed in the ashnime (and not in a over-the-top cliche way like in the Mewtwo movie "the creation surpasses the creator")