So after finishing this game I must say that the overworld difficulty, in terms of what HMs (and Rock Smash) you must have for navigation, along with navigational mazes and punishing speed-enablers, Crystal Kaizo is more forgiving than Emerald Kaizo was. There's no point in arguing over that, since other users posted about it, while SHF replied.
I tend to follow a self-imposed challenge: randomly selecting (through Google's RNG) 6 numbers from 1-251 (in Gen II's case), then checking the dex numbers and have my team for battle purposes (HM slaves were required). Then I go with that team on an itemless, set mode-only run. My squad was thus Charizard-Pidgeot-Fearow-Gyarados-Teddiursa-Wobbuffet.
I (almost almost) succeeded in Emerald Kaizo, having beat the game (Steven) with Slowpoke-Salamence-Alakazam-Porygon2-Omastar-Magikarp (before you ask, I banked on Ancient Power boosts vs Glacia, even had to change my Shell Armor Omastar to a Swift Swim one, otherwise I wouldn't have done it). The post-game superbosses were too much.
In Crystal Kaizo, I was forced to break my rules a number of times, namely:
It was so so frustrating, but at the same time very gratifying to beat a difficult opponent, which makes me think that the game, with no limitations (pokemon, items, battle options), is far from being nerve-wracking. Wobbuffet was almost always the MVP, and a must for any player who seeks a comfortable run. The only pokemon it cannot technically beat are Houndoom (immune to Mirror Coat) and Umbreon (faster, has Toxic, where Shuckle is slow and can be PP stalled). I had to beat a lot of trainers, but mostly the ones above, dozens of times to figure out their moves, items, AI, even cheese opportunities. Hell, Surge, SHF and Silver took me well over 100 times each.
Really liked the #252. Fun idea.
Team's final moveset (vs Silver):