>>50349500Gen 4 and 5 (B2W2 in particular) make fights hard by giving you opponents that can threaten you without a 10 level difference. This is primarily done by making most, though not all, of the bosses use actually good Pokemon, and the shitmon are still far better than in prior games. Yeah, Staraptor is a route 1 Normal/Flying type, but it's a huge threat due to GF actually balancing it, making Barry's Staraptor absolutely destroy the unprepared. Yeah, Watchog is a shitmon, but you fight one before most Pokemon even have a chance to evolve, and it uses a 140 BP Retaliate the turn it comes out, most likely OHKO'ing one of your Pokemon.
Johto, meanwhile, only has "challenging" fights if you're going into fights ridiculously underleveled. Due to the terrible EXP curve, you're actively encouraged to use less Pokemon so they remain competitively leveled.
