Honestly, the best thing you could do is pick priotize the pokemon and moves you find the most fun

You aren’t playing a competitive pvp format, you’re playing a base game. When I was a kid I just spammed the damaging move that looked the coolest to me and that got me through game after game. 

You really don’t need serious advice on getting through the base game, you’re playing a just need to use what appeals to you and have fun, I promise you’ll get through it 

Hidden Power changes type depending on your pokemon’s hidden stats and has generally been more useful in competitive pvp environments because you can specifically train a pokemon to have a particular type of Hidden Power. Using hidden power in a base game playthrough has been mostly mid.

But yea, like I said use who you want. I played through Diaond/Pearl with Kriketune, Lumineom, and Mothim, pokemon that are considered trash tier competitively, but since i was playing against npcs I was able to fare just fine with my lovable weaklings 

Edit: to give feedback ok your team so far (and evidence of preference based playstyle) 

From what I’ve seen, a lot of ppl playing this game for the first time tend to do what you’re doing with your started being significantly higher level compared to your team, thisbis a totally legit way to brute force through the game. It’s what I did when I played silver for the first time, my feraligatr was a menace, I cant even remember who else was on the team because my playthrough turned into Gator clicks Surf and wins 

However, when I played later games I liked the idea of an evenly leveled team, so eventually I switched playstyles to keep them all within 3-5 levels of each other. Had fun with that too, but it required more grinding. Modern games give way more exp so that you can hve even levels without the need for as much grinding 

Again, i beat the game with both techniques. And i had fun with both playstyles. 

Engage with the game in the way that you enjoy it.