Final update - I filled the Pokédex in Crystal Version as much as possible without trading or glitches. My legendaries easily defeated Red's high-level team. (Links to previous posts in comments) :
UkiyaSeed's Other Blog - Orends: Range (Temp)
Pokémon Gold and Silver head to Nintendo 3DS Virtual Console, trade and battle with local wireless - Neoseeker
Why Pokemon Gold and Silver are the best games in the series
How To Get Infinite Gen 1 Legendaries at Lv100 into Pokémon Sun, Moon, Ultra Sun, and Ultra Moon : r/pokemon
Pokemon Png Glitch Transparent Pokemon Gold Pokemon - Pokémon Silver Version Reproduction Nintendo Game Boy PNG Image | Transparent PNG Free Download on SeekPNG