I'm playing this game from about 8 months, and there aren't some object extremely needed!!!
1) Share exp: fast exp pokemon, but more than that, fast ivs training for all tank/wall pokemon (like chansey)
2) EGG: guys seriusly, breeding pokemon is 1/2 of pokemon's games, search some pokemon for pvp is an absurde spend of time.
3) FLYING: seriulsy why the hell we have to pay for travel?
Those 3 point don't make game more hard, they just make it more boring and frustrating!!!