Ok, that's a lot to consider. First, there should be no point in time where you are listening to a piece of music for more than a couple of hours without a change, so to claim it gets repetitive at 9 hours suggests you have lingered in an area. If you have a task that keeps you there, such as hatching, then flick on a livestream or some such and listen to that. A simple resolution. As for considering others, if that happened, then everything would be lollipops and rainbows. Next, I believe Ark thought you were referring to the enemies being underleveld, or that's the impression i get. Onwards, For Growlithe etc being underleveled, That is easily solvable if you play right. Hell, i don't grind either and when i was at samson, i had several pokes breaching 60s, whereas you seem to be mid- late 50s. It's all a matter of playing your cards right. You can get the low leveled pokemon exp, you just gotta know when to switch em in and out, it would also help to try and determine if you want to use it before hand, and then grab it ASAP to get the most use. Next, you say you cannot remember the badge limit, that is the extent of your evidence. I'm sure that until we hit samson, who did not raise the level cap, we all knew what the level cap was. It's a simple matter of paying attention to dialogue. Finally, for the natu issue, the game is amazing at having pokemon reside in their natural habitats, Psychic types, and a bird at that, would naturall be found in a natural sanctuary like citae, with the power brimming down there. What sentient bird other than pidgeons would stay in a city?
Me thinks that's most of it -.-
Also, you have access to the Day care as well, in case you wish to level a poke whilst breeding n egg, that helps tremendously at that point in game, though obviously not later on