Are they aware of what your fashion sense is like? —LH
Excuse you. I have an impeccable fashion sense. Also, you’ve clearly been speaking to my older sister, and I would appreciate it if you’d stop. Or at least tell her to give me back my jacket. How am I supposed to exude the aura of a steampunk mad scientist without it? —Bill
Is that what you were doing? —LH
Always dress for practicality, anonymous. Remember that you’ll be spending much of your time hiking outdoors, so you’ll need outfits that fit the typical climate and terrain of the region.
For example, Kanto and Johto are similar in terms of terrain and climate in that both are temperate areas with four seasons and plenty of mountainous terrain. (Johto is, incidentally, slightly more mountainous than Kanto.) What outfit you’ll need depends on the season, then, but always have a decent pair of walking shoes or hiking boots to navigate the more mountainous routes. Pants—regardless of what certain younger trainers will tell you—tend to be better choices than shorts shirts due to the prevalence of tall grasses in Kanto and ground-dwelling poison-, grass-, and bug-types in the forests of Johto.
Hoenn is far warmer and more tropical (despite being not that far from Kanto and Johto), and it’s far, far wetter. Shorts and short-sleeved shirts are best here to help keep one cool, and sneakers or waterproof shoes will help a new trainer navigate the sandier and muddier terrains. Keep in mind also that part of your journey through Hoenn will take you past volcanic areas and through an actual desert, so be sure to wear sunscreen and hydrate yourself.
Sinnoh, by contrast, is a far cooler region. Some areas are perpetually covered with snow, and the southernmost parts of Sinnoh rarely reach temperatures above 70 degrees Fahrenheit. Jackets, long-sleeved shirts, and pants are highly recommended, and consider bringing a warm coat if you plan on fully exploring Mt. Coronet and other northerly points. Additionally, some parts of Sinnoh are wetter than others. While traversing these, keep in mind that denim retains moister far better than other materials, so jeans are ill-advised (as wearing wet jeans can cool your body temperature to dangerous degrees, especially as you sleep in the cooler Sinnohan wilderness).
Unova is similar to Kanto and Johto in that it also experiences four seasons, but it tends to be somewhat warmer and dryer (and dustier…) than the others. Part of this is due to the giant desert taking up a large portion of the region, and other parts are due to the fact that Castelia and Nimbasa have the very strange ability of leaving anyone who passes through them with the distinct feeling of being covered in film. Long sleeves, pants, and walking shoes that are suitable for a large amount of use on concrete are ideal. (Yes, even through the Unovan desert. There are sandstorms there, and as such, you will likely regret leaving any part of you unprotected. On that note, pack goggles if traveling to this part of the region.) Also, be aware that the outer edges of the region are swampier and full of more coastline than Central Unova, so bring an extra pair of socks.
Kalos likewise is a more temperate region, but it shares many similarities with Sinnoh. Parts of it (namely Snowbelle and the areas surrounding Dendemille) are perpetually covered with snow, but other than that, Kalos is full of coastline, marshland, and forests, while the average temperature may be comparable to a sunny autumn day. Long sleeves and pants are likewise advisable, and a coat is essential for the more wintry areas (especially Route 17).
Finally, Alola is a highly tropical region and famous for being such. Its key attractions for trainers include lush rainforests, volcanoes, seaside caves, and plenty of coastline, as well as the perpetually snowy Mount Lanakila. Additionally, while most days are sunny, it’s not unusual to be caught up in a heavy tropical downpour, especially during the monsoon season. Wear clothing that will keep you cool but always keep a poncho close at hand. A coat is advisable if scaling Mount Lanakila, but it’s better to keep this in storage until you absolutely need it, as the rest of the region tends to be blistering hot. (Well, if you’re used to Johtonian temperatures, anyway.)
Otherwise, be sure to do your research into the region you’re visiting. Many trainers keep travel blogs to help newer crowds decide things such as what to pack, so it may be worth it to run a search on the region you’re considering.
Best of luck, new trainers!