You're not alone. I'm also confused.
It is absolutely fair to question, that being said, they seemingly know Oak/Gary to a decent point, and those two know Ash rather well, but also, as a random addon, he apparently will help them assess Gou in teamwork aspects (which could be done with other competitors/Asahi or Tsurugi mind you, but this is also a fine way to do that.
Asahi said it was alright for Ash to assist Gou on these trial missions since one of the things that will be tested during these missions is teamwork with other trainers. In fact, we've already seen this happen in the Moltres episode where Gary allowed Ash and Gou to help with his trial mission (even if Gary still did most of the work anyway).
Oh okay. But still: it's pretty strange how they just... let some random kids who aren't even part of it to tag along and participate in those missions.
It actually wasn't a Trial Mission. It was a mission to qualify him to start taking Trial Missions.
So a trial mission for a trial mission? Hum. I don't really know what to think about this. It's kinda interesting tho.
It's possible that they're only letting him tag along for these trial missions to test how well Gou can cooperate with other trainers, and the actual expedition on Table Mountain will only consist of the chosen Project Mew members + the leader.
I've seen the argument that Ash is there for Go to test his teamwork skills but that argument makes no sense to me. That’s basically the equivalent of bringing in your best friend (who's in an entirely different profession) to your office to show your boss that you have good teamwork skills.
While I wouldn't say that Ash is in an entirely different profession than Gou, I do get what you're saying. It would definitely make more sense to have Gou work with trainers that he hasn't met before if they really want to test his teamwork skills. With that said, it doesn't seem like the Project Mew team are too fussy about who the candidates are working with since they didn't mind that Gary was working with Ash and Gou during the Moltres episode.
Well, that changes the entire argument. The goalposts got shifted to "We're testing teamwork skills" to "They are welcoming all the help they can get". Then why exactly are they bothering to hold two trials for their members? It’s not as if when they find the exact whereabouts of Mew they’ll be like "Hey, Ash even though you’ve been with us for the entire project, this one is confidential and you won’t come with us." They should probably give Ash a trial as well. It would solve half the issues with this, or have Ash and Go do a joint trial that’s comparatively more difficult but needs teamwork for me to accept these justifications.
You're saying that as if those two things are mutually exclusive, when they're really not. Project Mew is a research team first and foremost, so if a trainer genuinely wants to help with their minor research operations (and occasionally search-and rescue operations too, it seems), they don't really have any reason to reject them. With that said, Mew is still their number one goal, and their expedition to Table Mountain will probably be quite dangerous, so they want to make sure that all of the expedition's members are up to the task. Hence, they're using these smaller research operations to scout for potential candidates for the expedition and test their capabilities in the field, with teamwork being one of the aspects that's being tested.
On one hand, that seems to be what they're implying. It's specifically mentioned that Project Mew will be consisting of 5 members only, so if they're still gonna let Ash participate in the actual expedition once all 5 members have been chosen, then that 5 member limit would seem... kinda pointless. Again, this is ignoring the possibility of Ash joining the fifth slot that's currently open right now, but I think it's much more likely that we'll see another character attempt to join Project Mew.
