It is easier but much more annoying because they can easily deny your effort by chucking gold razz berries.
I would advise:
* Add status conditions or move effects in the game so all pokemon have an equal chance of deterring opponents
* Add traits (Like in Pokemon Rumble) in place of abilities so battling becomes a bit more complicated (Also boosts Medicham to relevant levels until Gallade kicks in)
* If pokemon become too powerful in the future, allow 1 legendary per gym