Patches can allow Pokémon to evolve without trading, remove EXP limitations, or add Gen 6/7/8 features, similar to "ROM Hacks" like Pokémon Blaze Black 2/Volt White 2 .
Using custom firmware (CFW) via Twilight Menu++ is the gold standard for playing Black Version 2 today. pokemon black version 2 usa europe ndsi enhancednds patched