im that friend hahaha. mareep is outclassed by raikou, but i know peopel arent the biggest fans of using legendaries sometimes. mareep is a solid bet for an electric type. i dont suggest having rattata in your main team - use them as a HM slave, but dont keep them on constant. grab an extra gyarados for whirlpool/waterfall/whatever but dont plonk 'em in your main team.
if it's available in your game, try to get yourself a scyther. it's incredibly OP with technican, albeit its only available in the national park thing every few days. (if you need help w/ that give me a bell, i know the patch he pops up in the most).
my team in soul silver right now is typhlosion, scizor, raikou (formerly ampharos - ampharos is also a babe and gets fire punch FYi if you're low on that sort of coverage in your team), nidorino (waiting 'till he gets poison jab to evolve him, since i cant get it until kanto otherwise), honchkrow and gyarados (tho while i do love gyarados and his ice fang and all, im gonna switch her out before the E4 as her movepool is too limited for me to efficiently work with. stats are great though).
so since you have feraligatr, growlithe is great, and so is houndour - i prefer growlithe mostly due to propr experience. houndour has (at least in my experience) been a little frail, but they're not awful. they're useful anyway, and iirc houndour's moveset is a little more varied. geodudes good for leveling, but if you cant trade, switch him out for someone who doesnt need a trade to be at their best. i found he started losing his efficiency once i hit gym 5, but you could probably get him to last longer with the right moveset etc.
gastly is also generally great and does godo against morty. theres an ingame tiers list somewhere that i'll show to you on skype when i get in later, my dude, but i'll edit this post a 'lil later to offer my suggestions proper