Raiden, Astrid and the twins.

Neither Raiden or Astrid believed for a second that she was some weak innocent girl. Raiden knew for a fact as he could sense her presence when she entered his mind. He knew exactly what she was trying to do. He decided to quickly put a mental barrier around everyone from Berk. He then set up a telepathic link with everyone from Berk as usual. He then let them all know that the girl had psychic abilities and that she was literally messing with their heads. Astrid and Raiden began watching everyone closely waiting to see who would make the second move. The twins wouldn't sit and wait for somebody to make the next move. Ruffnut summoned a large thunder storm, it immediately began to rain heavily as lightning began striking the ground randomly making it hard for people to dodge all the lightning bolts. Tuffnut began making the earth shake violently compromising everyone's balance as earth spikes began to come out of the ground all over the arena, both the twins knew that these attacks would not hurt anyone from Berk as they left a small safe zone around them. This was to keep the people from Berk safe and to lure the enemy to them. Suddenly a large fire blast came out of nowhere from behind Dagur and the rest of the villains. As soon as the fire blast started spreading across the arena a large purple dragon appeared out of nowhere but it was obvious it was the one lunching the attack. Then a large amount of water was summoned and electrified. As soon as Astrid saw the electric surrounding Sabrina Astrid created a large ice dome around her and the others from Berk preventing any water from getting in, protecting them against the waves and the lightning. 

Dagur,

Dagur was getting excited, he could see that this battle would be entertaining although he didn't know why a little girl would join, even if she had power she would have no chance against all these heavy hitters. He began to get a little frustrated not knowing who to attack first, he began looking around for the strongest opponent when suddenly a large fire blast came out of nowhere from behind Dagur and the rest of the villains. As soon as the fire blast started spreading across the arena a large purple dragon appeared out of nowhere but it was obvious it was the one lunching the attack. Dagur used his dragon mimicry giving himself dragon scales making him immune to fire. Then a large amount of water was summoned and electrified by Sabrina. Luckily Dagur was already mimicking a Skrill to protect himself from the fire. This would defend him from the electricity as well. 

Sabrina 

Sabrina watched as everyone in the arena got ready to fight. She could sense the magic coming from the little girl. She knew she was stronger than she looked. She had already summoned a purple Nen dragon and used In, a advanced Zetsu technique which makes your Nen both invisible and unsensable. Once the dragon lunched the attack she stopped using In as it is a form of Zetsu meaning she could use her aura for defense while using it. She then used her conjurer ability to summon a large amount of water which filled up the arena, she also summoned a surfboard and began riding the large waves she was producing. She then changed her aura into lightning and sent strong bolt of lightning into the water electrifying everyone. Anyone who had no defense against electricity would receive serious burns and would be temperately paralyzed if not unconscious. 

Ryuji 

Ryuji saw the little girl enter and could tell right away she was no ordinary girl but then suddenly his opinion started to change, he started to see her as a weak little girl, he immediately knew somebody was trying to mess with his head. He figured it was the little girl. Confirming his suspicions. Suddenly a large fire blast came out of nowhere from behind Dagur and the rest of the villains. As soon as the fire blast started spreading across the arena a large purple dragon appeared out of nowhere but it was obvious it was the one lunching the attack. The fire had no effect on Ryuji, in fact he just sucked up and ate as much of it as he could. Then a large amount of water was summoned and electrified by Sabrina. Once again his Dragon Slayer magic protected him from the attack and once again he just sucked up as much of the water and electricity as he could knowing he would need all the strength he can get but before rushing into the fight and attacking somebody out of the blue he decided to look for a worthy opponent so he just sat and watched everyone.