So what's a good team for a first play through? There's a lot of options. Should I be giving magic to everyone in the party anyway? Is a full melee team suitable for the whole game?
At the moment I have Julian as my main. Nora, Ellen, Thomas and Monika. I want some magic users. I tried giving Monika and Thomas magic but it's taking forever to build up their MP and skill. Thinking of ditching either Nora or Ellen for a magic based character, But I like them both.
You'll generally want different terrestrial elements of magic (water/earth/fire/wind) on 2-3 members, each with the ability to heal either via that element and/or a celestial (lunar/solar) one. That'll keep up your team's healing capacity as well as their ability to neutralize the elemental field effects that heal bosses.
Thomas and Monika would both make OK mages, but raising MP is a slow-going affair; probably best to replace them if you don't want to invest in that process. There are plenty of good mages or hybrids to choose from: Undine(*) is a great all-rounder with her default Water magic, or an offensive powerhouse if given Earth; Charl starts strong in Fire (and needs to be given the Silver Hand equipment to boost his physical stats) and could be given Lunar/Solar for healing utility too; Boston is another powerful hybrid, starting strong in Water as well as Martial Arts.
(*): Undine starts with an MP crown, which deducts 1 MP from all her spell costs. Crowns are rewards for focusing a character on either SP or MP usage (physical or magical, essentially). It's a ratio thing -- characters who gain much MP can't get an SP crown, and vice-versa. So Undine's best left only casting magic. Interestingly, she has a bugged (?) affinity for Earth magic, reducing all its costs by 1 (doesn't stack with MP crown deduction), so if you switch her to that she could also use a bow or something since her crown would only help potential Lunar/Solar costs.
Nora and Ellen are both strong physical characters, though in similar ways. Nora's best with maces/axes, while Ellen's strong in axes/martial arts. Could use them both, or just one if you want weapon type variety. I'd pick Ellen, because Nora can be made into a blacksmith if not a party member.
Here's the character page from the best English resource for RS3 (if you don't want to spoil available characters, just navigate elsewherel):
https://romancing-saga-3.blogspot.com/p/rs3-characters.html