>>45403640Depends.
Emerald can be really, really hard from Maxie to Winona if you don't know what you're doing, and especially if you picked Treecko.
Platinum can surprise a lot of people, especially with that last Cyrus fight. That first Purugly also wipes teams, and Giratina can't carry weak teams the way Palkia and Dialga can.
USUM is a weird juxtaposition of asleep-at-the-wheel tier easy, and softlock-until-you-customize-your-team hard.
Colosseum probably takes the cake, though, as it manages to tag almost every possible avenue of difficulty. Everything is doubles, so it's easy to lose your star pokemon in a big fight. EXP gains are pathetic, and grinding is difficult. Your pokemon quality is sub-basement tier, besides one or two pokemon that are missable, or the pokemon from bosses. All catchable pokemon can actively kill themselves on the one hand, and have low catch rates and can shred your teams on the other. Entei, for example, can fuck your shit sideways itself, and comes after a team built around slamming you with Earthquake from shit like Golem and Camerupt, when your team likely is around 34, 35, with maybe your starting, frail as shit Espeon as your best answer to it. Good fucking luck catching it with all the great balls your limited funds can afford. Bosses have teams with actual thought put into them, with pokemon quality WAY above yours. The final stretch of the game is a 5 trainer gauntlet that is to this day probably the single hardest thing in non-romhack pokemon. SKILL SWAP FUCKING SLAKING ON THE CHAMPION, people. One or two misplays, with your team of underlevelled shitmon can set you up for a wipe against any of the last 3 trainers of that gauntlet.
And did I mention how shitty your own pokemon availability and exp gain is, yet? We're talking your level 33 Ampharos being the anchor to your team for like, a third of the playthrough.