In Pokemon GO's latest update, you can summon your faction's trainer from their busy schedule to come and check out your Pokemon. While their advice seems broad and mostly useless, you can actually use it to calculate the exact hidden stats that your Pokemon has. As the How-To Geek points out, the faction leaders will give you coded statements that give you a general range of where a particular stat lands. For example, Blanche above tells me that my Weedle's HP is its strongest aspect and then says, "Its stats exceed my calculations. It's incredible!" This indicates that this particular Weedle has a perfect IV (or individual value) for HP. The site has a full list of what each piece of dialogue really means below.
Once you have the general ranges that correlate with each coded statement, you can plug those values into the previously mentioned Poke Assistant IV Calculator. These numbers will help you calculate your Pokemon's overall level, as well as figure out how well it might do in battle at a gym.
It's slightly more complicated that most Pokemon games' usual method of, you know, showing you your Pokemon's level. Still, it's nice to know that those trainers aren't just showing up with useless dialogue. Check out the How-To Geek's full guide below for a ton more info on this topic.