Tehdood

Current team is Ivysaur (22), Fearow(27), Horsea(25), Paras/Snubbull (HM Slaving).I just arrived in Vermillion and following the Kanto story walkthrough. I am trying to build a rounded team to get me through the story first and then worry about the E4 later once I'm more established and have resources to grind with. The issue I am having is that my team feels weak unless I have a type advantage. Against normal pokemon it feels like a toss up. Sometimes I crush them and other times I seem to get the short end of the stick. Trainer battles are tough if I don't have any type advantage as well and I've been knocked out quite a bit. I feel like I'm doing something wrong or missing something. Not sure how to proceed at this point as the team feels weaker and weaker the farther I progress in the story. I did ask this same question on the Discord and all I really got was, "Get Gengar and Gyrados. All you need for Kanto and don't evolve until 95, then use Rare Candy". Problematically this doesn't really mean anything to me as a new player. After searching the Discord I've noticed this seems to be the go to answer but no one seems to want to explain how it works in practice. Searching Google also doesn't return much of anything either. I'm contemplating restarting on a new account so I can pick a less weak starter or going back to the lower areas to catch other Pokemon I may have missed.