you need two or more Pokemon to battle them as it is a double battle.
mossdeep city, to get there, surf east from lilycove also it is a double battle because they are twins Gym Leaders Tate & Liza
In Pokémon Omega Ruby and Pokémon Alpha Sapphire, the Pokémon that the two Mossdeep City Gym Leaders (Liza and Tate) will have once you challenge them to a battle and it will be a Double Battle will Lunatone and Solrock, Solrock will be at Level 45 and it will know moves such as Solar Beam, Sunny Day, Psychic and Rock Slide and Lunatone which is also at Level 45 and it will know moves such as Calm Mind, Hypnosis, Light Screen and Psychic.
Dive is obtained from defeating Tate and Liza at Mossdeep City's Gym.
Tate and Liza have on Ruby and Sapphire: Solrock Lunatone On Emerald they have: Claydol Xatu Lunatone Solrock
You have to surf from Lilycove to Mossdeep city so you can challenge the 7th Gym Leader, The psychic twins, Tate and Liza.
I dont really know what you mean. Mossdeep City is in Pokemon Ruby, Sapphire and Emerald. It might be a game glitch or maybe a cheat gone wrong (If you've used any).
Steven stone lives in mossdeep. go to his house ( the one at the northwestern part of the island) and he will give it to you. BUT you need to beat liza and tate, the city's gym leaders, to use it.
The HM containing Dive is given to you by Steven Stone in Mossdeep City. Be aware that the gym leaders Liza and Tate must have been defeated before the HM can be received.
After beating tate and liza head to steven's house in mossdeep city he will give you the HM Dive.
you get it from Steven once you defeat team magma at the rocket place in mossdeep after defeating the gym leaders liza and tate.
Defeat Team Magma in their hideout at Mt. Chimney's Jagged Pass and defeat Team Aqua in their hideout at Lilycove City to be able to travel to Mossdeep City. Mossdeep is east of Lilycove; you will need to Surf to get there.The 7th gym is located in the Mossdeep city. From Lilycove, travel the seas with "Surf". Keep travelling to the right and your will soon get to the Mossdeep. Go up ahead the Mossdeep area and you will find a gym. Inside is Liza&Tate. They hold the Mind Badge. The Mind Badge allows for the HM Dive to be used outside of battle. Additionally, it will raise the special stats of the player's Pokémon.
To get to Mossdeep You will have to beat Wiona and then go to Deford and keep on surfing east. When you beat Tate and Liza you can either go strait to Sootopilis City or surf south then west to Pacifilog City Hope I Helped!!!!