Upon arriving in Hoenn, you need to note that you won't be here long. Unlike the other regions, this region will not be three parts.

Starting off, track down the Dexters. They won't let you near the base, but you can find Emerald in Mossdeep. He'll point out the problem. A large monster was fighting on the mainland. Ruby and Sapphire were holding up two sides of the battle. Guess what? You have two choices: Split your team up or just assemble one and fight two battles. Technically, you don't have enough people to split the team up and unless you chose a specific team (Not exactly mine... but pretty close to it), you aren't going to get far trying that. There is actually a team that can get you the option of two teams (Cedar, Crepe, Scarlet, Mauve, Red, Gold, Pearl), But I doubt anyone chose that team.

Moving on, you will start with Sapphire's side. While Sapphire isn't the strongest, she can support like a firestorm. 90% of the Combos she has are all heavy hitting attacks. So use her to her full potential.

Ruby's side is different. Similar to the 11 turn fight you did with Cedar, this will be like that. Only, it'll be a 26 turn fight. Ruby will be charging for 26 turns and you have to protect him. All units should stay focused on protecting him rather than striking. Unlike Sapphire's side, Ruby's will counter and heal the same damage or double it. So be careful about your attacks. Ruby's the only one to pierce the beast's counter, so support and protect him as best as you and DON'T ATTACK! Upon the 26th turn, he will blast the beast's other side and finish the battle.

Meet back up in Mossdeep and run through the Dialogue. Ruby will leave early upon a second beast. Sapphire will disappear near the end thanks to a third appearing and Emerald tracked a fourth.

In order with Ruby, Sapphire, Emerald; join in the fights. Ruby won't have time to charge, so hammer the beast with everything you got. Sapphire's will run the same, use her combos to the fullest. Emerald's will be interesting as he supports the team. Use this to your advantage and focus on the heavy hits.

After finishing, get back to Mossdeep and get your choices for a companion.

Ruby: Heavy hitter, can take over a battle

Sapphire: Combo master, able to help the team through a zone and can track anything

Emerald: Support master, can track and gives optional dialogue options

Afterwards, You'll head to Unova and do the trio regions over there.