Pokemon Sapphire Team Improvement Help?

Hiya everyone! I randomnly started playing Pokemon Sapphire again on my Gameboy and I’m hooked. I always have trouble with picking a team and I have absolutely no idea what to do. I would like a balanced team with different weaknesses but I don’t know which types/Pokemon to pick!
In the game I have just defeated Team Aqua at Slateport near the Mueseum.

Here are my current Pokemon in my party:
Electrike 12
Ralts 14
Taillow 14
Zagzagoon 14
Torchic 15
Lombre 15

I would love to keep my Torchic and my Ralts, but if you have legitimate reasons for me to put them in my PC then I’ll keep an open mind.

Thank you!!!! :)