At the early levels, it's relatively easy to advance in Pokémon Go without spending any money. Provided you're not in a Pokémon-light rural area (or, er, a black neighborhood), it's pretty simple to just keep farming Pidgeys and nearby Pokéstops and gyms for the resources you need to watch your in-game numbers go up.
Now that the game has been out for more than a week in many regions, though, some of the first players to hit the game's higher levels are running into a wall that's halting that easy advancement. In a detailed Reddit thread discussing his "late game" progress in Pokémon Go, user Riggnaros discusses a few ways the game grinds progress to a halt once players hit level 25 or so.
For instance, Riggnaros says, once you reach a level in the "mid 20s," low-powered Pokémon you encounter in the game start to "have an abnormally high chance to evade capture." That means players will need to start wasting a lot more Pokéballs to capture the most abundant monsters, which are key to gaining the experience points needed for that next level. Getting enough Pokéballs to keep up with all those escaping Pokémon means spending real money or spending inordinate amounts of time farming free Pokéballs from those slowly refilling Pokéstops.
Read more here http://goo.gl/7pf1sy
