Lugia - The master of the seas, he's at one of the highest catchable levels in GSC! The greatest thing about him is that he's dual Psychic and Flying type, but mainly uses Water and Flying-type moves. Belive me, I captured him in Crystal. He's in 5th place.
Chikorita - It's not a good choice in the beginning of GSC, but it's an epic Pokemon like it's evolutions after! Not much to say, but I chose it in Crystal, and it's my strongest Pokemon (at least it is). Chik's at 4th.
Sneasel - Sneasel is one of the best Pokemon, and you can capture it earlier in Crystal. It's a dual Dark and Ice-type, and what's even more amazing is that it can learn both Surf and Cut! With its icy and dark powers, Sneasel's at 3rd.
Totodile - This little guy packs a powerful punch... or, in its case, bite. Its the tallest Water-type, and evolves into some pretty epic Pokemon! It is a good choice in the games. Totodile's in 2nd place.
And the lucky Pokemon at first is.... HAUNTER! Haunter has always been one of my all-time favorites, and is also in the trio of Gen. I Poison/Ghost-types! It can learn Hypnosis, and then Dream Eater, a useful combination! My Haunter doesn't know how to use Hypnosis, but my Clefairy helps by using sing.