I’ve been playing these using an emulator, and I’ve noticed something. The game does not provide enough ways to level up your team for the latter portions of the game. The first two gyms are cake (as long as you didn’t pick Chikorita), but after that, things get messy.
Whitney’s Miltank is a Stomp whoring bitch, Morty’s Gengar will one shot Shadow Ball you into oblivion, Chuck’s Poliwrath takes way too much damage, and Clair’s Kingdra is just annoying. By the time I got to Chuck, my best pokemon, Quilava, was only around level 24, since I kept every one in my group around the same level. I still beat him, but it was at that point I noticed the gap between my power and that of the gym leaders’ really start to grow. When I got to the Elite Four, their first guy’s weakest is at level 40, and I’m still sitting with my best at around 38. This sucks, but it’s avoidable. Unfortunately, to counter the extreme lack of trainers to level your team up, you need to have patience and a lot of spare time.
In essence, you need to grind. A lot.
My plan for leveling up? Spend half an hour to forty five minutes before each gym just running around in tall grass, killing everything in sight. Level up one pokemon at a time to at or just above the toughest pokemon the Gym Leader hast offer. Do this for the two or three members of your team that’ll be most useful in the coming fight. For the others, get them to around two or three levels less.
By the time you’ve reached the Elite Four, your team should have an average level of around 43. While you won’t be at the Champion’s level, you’ll be close enough that when you fight him you should win if you play your types correctly. By the way, you want ice attacks, and lots of them.
Of course, without the right grouping, there’s little hope of getting far. The best team I know of consists of the following, and I’ve played Silver/Gold enough to know this stuff.
First, take Cyndaquil as your starter. When you finally have pokeballs, catch a Pidgey, and get a Geodude as well. Get both to level 11, since that’s when Geodude learns Rock Throw. In Sprout tower, grab a Ghastly and once you leave Violet City, you should find a Mareep. Bugsey is cake for a fire type, and Bug is also weak to Flying, so your Pidgey/Pidgeotto can act as backup. Ater Azalea, pick up an Abra south of Goldenrod, and a Machop if you can’t take down Whitney without a fighting type.
The sixth pokemon is your choice, though you’ll want a water or grass type until you can get your hands on Suicune/Raikou/Entei or Lugia/Ho-oh. The red Gyarados outside of Mauville City would do, but personally I recommend Lapras in Union Cave, since it’s part Ice and you’ll need the HP and the Ice attacks to combat the dragon types you fight late in the game. When the opportunity to acquire Lugia comes along, do so. He’ll be a huge help. Get rid of Pidgeotto/Pigeot and by this time you should be set fo the Elite Four.
You can avoid some of the grind by skipping the fourth gym for a while. You need the badge to use Surf, but you don’t need it to leave the city and go east or west. This is by design as the trainers in both directions have pokemon around the level you’re probably at if you haven’t done enough grinding. If you have, this is just gravy. You can get to Olivine and go up the lighthouse and to Mauville and clear out Team Rocket.
If you do these things before Ecruteak, Morty, Chuck and Jasmine might as well be rugs to step on. Pryce is where Quilava/Typhlosion come into play, but keep Lapras up to speed as his Piloswine has Ground type moves to counter fire. Clair is where your Lapras shines, and if he levels up a lot, don’t worry. You’ll still need him for Lance, the League champion. He is a dragon master after all. If you catch Lugia/Ho-oh, your time with the Four should be easier, but not foolproof. Always keep a nice supply of Potions, Full Heals and Revives handy, and find as many TMs as you can. You never know when a strange choice becomes a powerful one. Good luck!