For example, Sheer Cold is an Ice-type version of the Overheat/Draco Meteor/Leaf Storm archetype.

To make some moves, such as OHKO moves or Hyper Beam type moves into more useful and varied moves. Though non-Johto Pokemon appear in basically every route, they are more uncommon than the Kanto and Johto generation Pokemon. More Pokemon will be found with items in the wild, and more total types of Pokemon will be found in each route. To add more depth to some aspects of the game, like having more trainers able to use items on their Pokemon (either healing items, buff items like X-Attack, or status healing items) or having more Pokemon that you fight hold items that make the battles more interesting. This needs to be done to make up for the increased difficulty, otherwise some total losers like Ledian would go from 'pretty bad' to 'would be a liability to have on any team.' To be more friendly towards monotype teams by varying Pokemon available much more. Starter Pokemon evolve later than they did, but they also learn better coverage moves than before. Trainers have more custom moves, AI levels are higher in some places, levels scale up faster, and gym leaders and the Team Rocket executives should feel like boss fights.

To introduce a level of difficulty harder than the original.

To make all 493 Pokemon obtainable without trading. This means moving egg moves or tutor moves that would generally only be obtained after the first playthrough into the base movepool. To make Pokemon movepools more optimal for the first playthrough. I don't want legendaries thrown at me on route 29 or anything like that. To make a hack that doesn't feel too much like a hack.

Pokemon soul silver gba zip