Those are probably the ones worth mentioning. Please tell me which would make a reliable team. I don't mind adding a new Pokemon, changing movesets and EV training all over again.
Thanks in advance
While I've played the later gen facilities very seriously, I've never really put together a top tier Emerald Battle Tower team, and it's been a long time since I've played Emerald. So I'm not an expert. But I'd suggest the following:
Toxic Stall Milotic can be very good, and Dragon Water Steel tend to form a pretty solid core. I'd be inclined to say something like Latios / Metagross / Milotic would be a reasonable first draft team. Unfortunately, Latios really likes to outrun things, which it will do less often with a neutral nature, but it may still be your best bet, as the other Dragons all suffer from Dragon-type attacks being special attacks in Emerald. Still, it might be worth trying the various Dragons with Milotic and Metagross and seeing how they each play. If I recall properly, in Emerald you can get Dragon Dance onto Salamence by breeding a female Salamence with an Alatria (which learns the move by level up), so if you want some set up potential, DD mence is a possibility. Aerial Ace is a passable STAB attack on physical mence, too, since breeding for HP Flying is an enormous pain. With respect to other move issues, I'm typically partial to Thunder and/or Ice Punch on Metagross. I wish Iron Head were available in Emerald too, since the accuracy of Meteor Mash can cause problems, but Meteor Mash / Earthquake / pick two of Thunder Punch, Ice Punch, Exposion should be solid. Thankfully, I believe the punches are frontier tutor moves, and so should be available. Dragon Claw may be a better choice of STAB move on Latios than Psychic because of its generally better neutral coverage, and Surf and Recover are also very appealing, but it probably will take some play testing, as well as seeing where the coverage of your other Pokemon is lacking, to settle on the best moveset for Latios, since Calm Mind, Psychic, Ice Beam, Thunderbolt, Dragon Claw, Surf, and Recover all have their advantages.
Best of luck!