Well, the fact that ash loses isn't something, but losing for a spin off character that's only built around fanservice (Stereotypical looks, mega zard X, almost always win, quite edgy side) is something else. I mean c'mon, Alain was a spin off character who magically did jump in the XYZ series and rekted everything like this was childplay.
Unlike any other series, XYZ was the one we could see lot of trainers developing, like the trio with the kanto starters (tierno and the others) and that mega sceptile guy for example, but no. Let's just put a random character that wins everything and that's all.
Tobias kinda had the same issue, but still, Ash wasn't that experienced and more, they were not as many trainers with evolution through the arc, so it kinda feels okay to make a random win.