xMistyx: Here's something a little unusual for you. (First off, I assume you're not playing in Winter, or this challenge could be difficult or impossible without waiting a month.) For one of your slots, instead of dealing with a single Pokémon, you must use a Pokémon that can be anything you want, but must be immediately released before entering a city (or boxed and never used again if it refuses to be released due to being your only Pokémon who knows an HM move). For instance, you could catch a Patrat for this slot in Route 1, but would then have to release it before leaving Accumula Town (note that you can freely use it while in Accumula Town, though). You will be changing Pokémon in this slot a lot, because none of your other Pokémon can ever use HMs. (That is, if you want to use an HM for any reason, you have to freshly catch a wild Pokémon for this slot and teach the HM to it, unless you have a Pokémon in that slot already, in which case it had better learn that HM or you'll have to backtrack.) No evolution restrictions, if you really want to grind a Pokémon that far. You must also solo at least one Elite 4 member's Pokémon with the Pokémon you have in this slot (caught on Route 10 or Victory Road). If you backtrack for any reason and pass through a city, you must release this slot again before leaving the city you backtracked to. EDIT: Oh, and if you play the game long enough (especially, if you continue to the postgame), you'll realise why this has a water theme eventually.