F2P, grinding a lot since I started, back to February. By april, I was reaching Top 250/100 in past PvP and gettting all the LRs since then. And there are a lot of people like me. Yup, not everyone can be so grindy or have the patience to stay F2P in this game, but it is certainly posible. And yeah, I believe this game was really F2P friendly since I started playing, event mons provided me the tools I needed to achieve my goals and get what I have now; heck, it was somewhat hilarious when i noticed how I wasn't really strugling in Legend, while some people with over a year of P2P had troubles (this before the cicle of OP PvP Leaders started a month ago).
tl;dr: Hell outta grindy game, but really F2P friendly in my expierence of 6 months.