And that was ripped off from Blaine in Gen I. Gen IV had one that was a ripoff of Blaine as well. Every gym puzzle in Gen VI was something from Gens I-III. At least the Sophocles trial was a new take on it. I was always able to play through without sound before this.
Kiawe's trial was obviously a joke, Mallow's could have been a PITA if you didn't know where to find stuff. That one took me almost as long as the others combined. But it was different.
Just because it's a quiz doesn't mean it's a rip-off. They involved completely different types of questions. It wasn't hard, but it was fun, and the gym looked amazing, like most of the XY gyms did. Sophomore's trial was just three questions (or maybe four) that required you to beat a wild pokemon, which isn't more exciting than beating a trainer, because trainers can actually talk, have a personality, use items and have more than one pokemon.
It makes no sense for a serious character like Kiawe to have, if you allow me to borrow your words, a joke as a trial. Keep in mind that a quest can be both funny and exciting, one thing doesn't exclude the other. I agree that Mallow's trial could be a challenge, and it's actually one of the few i liked, but the fetching quest is unoriginal for a rpg and it doesn't really compensate for the others trials being so lame.
I will give something to the trials though and it's that they are far better at displaying the captain's personality and his/her background than the gyms were.
Grinding is not necessary to beat the game, but it's necessary for other things, such as learning moves, evolving pokemon, using bottle caps and etc... Therefore, it does affect the enjoyment of the game.... I've beat the game and haven't had to grind even once.
Not to mention, in most previous Pokémon games there weren't many grinding places either.
I don't know which games you played, but the previous games certainly had lot of places to grind thanks to the battle restaurants and battle chateau (xy) and lots of rematchable trainers (oras).