Can you get Articuno in Crystal? Damn favourite.
Ok, obviously, that one is a bit over the top, considering it not being particularly easy to get...
Wish I remembered my old Gold party, before I horribly mutilated it with a plethora of "legendary" Pokemon.
One particular favourite of a play through Silver (I had both games) was Arcanine. Fast, powerful. Though, IIRC, don't they appear late in the game - after the E4?
Staryu/Starmie were also ones I was fond of. Being pretty versatile with its special attacks (Water, ice, psychic, thunder), it could do a good job in a pinch. Being fast, with high defense, meant it was retty dangerous. Staryu is found in some water, commonly; Mahogany or Olivine (Towns? Been a while).
One thing I tend to do whenever I play through the games is catch ONLY the Pokemon I want, unless it's rare (In which case I'll deposit it in a box ASAP). Good thing? I can focus on the ones I give a damn about. Bad... well, tends to take a while until I get a full party. My last playthrough Silver, I didn't have a full party until the 7th Gym. Though it does wotk rather well, since I end up with a few Pokemon of high level (Beating the second leader by some 5 levels, the most extreme was being 10 levels higher than a leader during Pokemon Diamond).