Oh, here we go.
All those years ago, way back in my Silver, I'd went around searching for the single Pokemon, which I so dearly wanted after I had seen it wipe out my my big brother's team multiple times in a battle against one of his friends, and as I at the time at least thought my brother's Pokemon were pretty strong, I thought that was pretty darn amazing. For those curious, (and to actually answer the question), that Pokemon was Lugia. And it's my favourite Pokemon. Period. In all seriousness, even though it was the first Pokemon I even got to see when starting up the game for the first time, I didn't even find it before I had beaten Red, which I'm still pretty surprised over, as knowing me, I usually go legendary hunting as early as possible. Anyways, once I had actually found Lugia, I was not the least bit surprised over how strong it actually were, as from what I mentioned above, someone beat my brother's team, which consisted of well trained, close to level 100 Pokemon, almost on its own. This is just for what I recall, but I'm pretty certain that was what happened lol. But yeah, it came to be the Pokemon I used the most throughout the time I played it, and I had it traded over to my brother's game before restarting to play the story again, as I wouldn't let that exact Lugia go.
I have great memories of using Lugia in my Silver, and though I may not own my Silver anymore, that's not something I'll easily forget.