Fun facts:
1. You can get all 3 starters by using the cloning glitch early on in the game.
2. In Crystal, you get an Odd Egg which has a high chance of being a shiny. By using the cloning glitch you can get a large amount of eggs, and guaranteed shiny Magmar/Electabuzz/Tyrogue/Jynx, etc.
3. Gender plays a role in determining the Attack IVs. A female has 0-7 IVs whereas a male has 8-15.
4. Defense Curl boosts the attack of Rollout.
5. Earthquake hits through Dig, and Thunder hits through Fly.
6. You can use CUT to literally cut grass like in Zelda.
7. Gen 2 introduced swarms. By checking the TV once a while you might get a message of a swarm in a certain route.
One of the reasons I like gen 1 and 2 so much is because it's easier to max out your Pokemon. No Nature/Ability/EVs to worry about.
Also if you're emulating Crystal, make sure to get the "Emu Edition" romhack by LocksmithArmy. It makes it so all 251 Pokemon are available to catch. And please do not use VBA, use a proper GBC emulator: BGB.