I agree with the "hard" mode, but I don't.
I'm into competitive battling. And I hate grinding. I mean it, I'll 100x prefer a simulator like PO over the real thing, cause it just takes so much damn work.
If hard mode = more levels, then no.
You want to know why?
Because in Leaf Green, I just crushed the elite four with nothing more than a Sunny Day + SolarBeam Venusaur at LEVEL 47. And the lowest leveled pokémon in the LG/FR elite four is 52/3, if I recall. Using basic competitive strategies (like toxic stall with my dodrio, sun abusing with my venusaur and doing the same with sandstorm and my sandslash + sand veil + double team) crush their terrible AI. And uping the levels won't change that. Yes, it may turn an OHKO into a 2HKO or even 3HKO, but that just makes us grind more, and that's boring.
Up the AI to competitive levels (as in Taunt not ****ing over any goodness in the AI they have already) and that'll be a challenge. That would be the only reason I'd even do a pokémon hack = uping AI, putting less trainers but better ones, every item in-game (scarfs, life orbs, leftovers) in lower-prices and let your head play instead of weeks grinding for a weak E4