2 months  later

Mario, Sonic and the others were finally experienced enough and have 6 gym badges already. However Mario and Sonic heard there was  something going on at central city. So they went there to see what's going on.

At central city.......

"Huh?,....Dr.Eggman ", Sonic said surprised to see the evil doctor once again.

"What is this madman doing here?", Mario said.

"Ah!...oh it's you idiots at least show some respect",  Eggman said.

" Why should we ?" Sonic said.

"Hmph, irritating me as usual I see. You two persistent punks should stay out of my way."

"Or else  what?, you say that like you  can't stop us which is actually true.", Mario said.

"So you fools have those pokemon? ", the doctor asked.

"How did you know?!", Sonic said a bit surprised.

"Fool!, those weird creatures started appearing here months ago." Dr.Eggman said.

"So Egghead, what're you planning?", Sonic asked.

" Like I'll tell you." Just capturing  something living high in the sky.

" You're planning on capturing mabye a powerful pokemon living in the sky?",Mario guessed.

Eggman was caught.

"How did you know?!, anyway you can't stop me."

"What makes you think that?", Sonic said.

"Because first of all, I'm gonna beat you in a pokemon battle. Second of all I'm gonna keep you busy. Dr. Eggman then presses a button in his egg carrier and 3 guard robos appeared from Sci lab.

"Sonic, you take care of Eggman,  I'll handle these bucket of bolts.", Mario said.

"Ok", Sonic replies and runs to confront Eggman. "So Egghead, what pokemon do you have?"

"Why don't you see for yourself. But I must warm you, they're strong.", Eggman said.

"Ok. But I'll still win, egghead.", Sonic said.

"(😠) Stop calling me egghead!!!", the doctor said furiously.

"Sorry egghead", Sonic says.

"You're still saying it. Nevermind!!, let's get this over with.

The battle started. Sonic brought out geodude and Dr.Eggman brought out "Aron", geodude used tackle but it wasn't effective,  Aron used metal claw and geodude fainted. Sonic bright out torchic and told it to use ember,however  Aron dodged and used headbutt sending torchic flying , Aron ran and gave torchic a full charge  tackle. It then used "iron defense" to raise it's defence twice as normal. Torchic got up but it was feeling weak before it realized Aron used rock throw making torchic faint. Sonic brought out ekans and told it to use glare making Aron paralyzed,  ekans used bite but it wasn't effective but it made Aron flinched and took some damage. Ekans used wrap and it was a critical hit and Aron fainted. Dr.Eggman brought out kadabra and told it to use "psychic", it was super effective on ekans and it fainted. Sonic brought out a poochyena he caught earlier and told it to use bite, it was super effective but it wasn't enough to make kadabra faint. Kadabra used "telekinesis " but it had no effect on poochyena. Poochyena used bite again and it was a critical hit and kadabra took a lot of damage, poochyena used tackle and bite again and kadabra fainted.

"I see you're an experienced trainer", Eggman said. "But not strong enough to take down my remaining 2 pokemon", Eggman throws a pokeball and a hitmonlee comes out.

Sonic surprised to see a new pokemon takes his pokedex and reads about hitmonlee.

"This is a fighting pokemon. Now I'm confident I'll win. Hitmonlee!...Comet kick!", Eggman commands.

Hitmonlee does a Comet kick sending poochyena flying to hit the wall. Hitmonlee does a rolling kick and poochyena faints.

"Hmm, you think you're strong?. I'll show you a true fight." Said Sonic. He then throws his pokeball releasing frogadier. "Frogadier!..use water pulse."

Frogadier uses water pulse sending hitmonlee sliding back. Frogadier then uses cut and finishes it with mega punch and it faints. Dr.Eggman then brings out "metang.  It uses "iron head" sending frogadier flying to the wall. It then uses psychic giving reindeer a lot of damage. Metang then does "metal sound" but frogadier dodges it. Frogadier then does water pulse and gives it all it got but metang uses "meteor mash" but frogadier dodges it and uses a new move,"hydro pump". Frogadier repeats it sending metang flying to the wall and frogadier uses slash and water pulse. Metang faints.

"What?!!, no!!!, how did I lose to you?!", Dr.Eggman said fustrated.

"You're not that strong. Looks like you need to train more." Said the victorious hedgehog.

"I'll show you who needs to train more" Dr.Eggman says before going into his egg carrier and starts shooting homing missles at Sonic.

Sonic dodges the missles and performs a homing attack which seriously damages the egg carrier making it emit a lot of smoke.

"You're going to pay for this!!", Said Dr.Eggman as he leaves the place quickly with his wobbling egg carrier.

" Ha!,...yeah you wish" Sonic taunts. Sonic then looks at frogadier and to his surprise, it was evolving.........it soon evolves to...."Greninja"!!!  "Wow!!", Sonic says excited and takes his pokedex to look at the description of Greninja.

Mario soon comes after dealing with Eggman's guard robos. "So your reindeer has evolved?"

"Yes, it has evolved to Greninja", Sonic replies.

"Mabye mine will evolve". Mario then looks at his charmeleon and to his surprise it also was evolving and it soon evolves to Charizard. Mario also checks his pokedex and reads the description about charizard.

Sonic then suggest  they should go back and rest. Mario gave Sonic a headstart and rides on Charizard's back and it flies full speed taking Mario back to the castle.

"Lucky him",Sonic says before putting his Greninja back in its pokeball and zoomes  ultra sonic speed back to the castle.

After 2 hours of relaxing. Mario and Sonic ventured to get  their remaining 2 badges so that they can go to the pokemon league. They went to Max's gym. A gym leader excellent with fire type pokemon.

At Max's gym........

After defeating some trainers in the gym,Sonic confronts gym leader Max.

"Nice, new trainers" Max Exclaimed.

"So you're the gym leader?", Sonic asks.

"Yes", Max  answers. "I can see you want to challenge me. My spirit burns hotter than volcanoe, I'm excellent with the fire type pokemon."

"Ok, can I battle you? "Sonic said.

"Yes, after all isn't it the reason you came here?", the gym leader says getting ready to battle."time to turn on the heat."

The blazing battle started. Sonic brought out his poochyena buy it was utterly defeated by Max's magmar. Sonic brought out combusken which was his torchic that evolved earlier. Combusken uses "double kick and "triple kick". Magmar took heavy damage, it retaliated by using "flamethrower", but combusken dodges it and used "peck". Combusken used double kick again then uses quick attack and magmar fainted. Max then brings out "numel.  It used "earthquake" which was too powerful and combusken fainted. Sonic brought out Arbok(evolved form of ekans which evolved earlier) and it used " iron tail " giving numel heavy damage . Arbok used "poison sting". It used wrap and numel fainted. Max brought out "Arcanine" and it used flamethrower giving Arbok some amount of damage but it sustained a burn but due to Arbok's ability" shed skin", it shed its skin, healing it from its burn. Arcanine used "flame wheel"  giving Arbok heavy damage and it fainted. Sonic brings out graveler and it uses rock throw giving Arcanine serious damage, graveler used earthquake and Arcanine fainted. Max then brings out his last pokemon called Blaziken a fire and fighting pokemon( also the evolved form of combusken). Blaziken uses triple kick sending graveler to the wall and finishes it with mega punch making it faint.

"Wow, you're strong...but I'm even stronger.",Sonic said before throwing his pokeball releasing his last and strongest pokemon, Greninja and it stands there in a unique fighting pose

Note: Greninja stand in the same fighting pose just like Ash's Greninja in pokemon XYZ.

"Hmm...at least this pokemon looks strong, but prove it", Max said.

Sonic commands Greninja to use hydro pump sending Blaziken to hit the wall and fall down but it gets up.

"Wow, you have potential.....,Blaziken  flamethrower!', Max commands.

Blaziken uses flamethrower but Greninja uses water pulse to penetrate Blaziken's flamethrower and hits Blaziken, sending him flying back.

"What?!", Max said surprised. "Blaziken use triple kick!"

"Greninja dodge it!.... use cut."

Greninja listens to Sonic's commands and it dodges Blaziken's triple kick and uses cut and Blasted Blaziken with a strong hydro pump. But Blaziken came back quickly and gives Greninja a mega punch sending it to crash the wall.

"You'll have to do better than that to bring Blaziken down." The fire gym leader said.

"Are you sure?, Greninja hydro pump!" Sonic commands.

Greninja does another hydro pump but this time Blaziken blocks it and runs full speed to give Greninja a "blaze kick" making Greninja fall down but it gets up, runs and uses cut but Blaziken dodged and counters with slash followed by a mega kick sending Greninja flying to the wall.

"Greninja......don't give up." Sonic said.

Greninja gets up then it starts feeling feeling energized. It runs full speed towards Blaziken and does a new move called" Water shuriken" Blaziken tries to block it but the move break its defences and it fell down. Greninja then attacks Blaziken with a quick attack, water pulse and another water shuriken. Blaziken fainted.

"You're a powerful trainer. You were strong enough to put out my flames. Since you won , I'll award you the volcano badge."

Sonic takes the badge." Thanks , but you weren't that bad either."

After defeating Max,Sonic went to the park where he saw Mario who was training his other pokemon.

"Hey Mario..what's up?", Sonic says.

"You're here, so you defeated the fire gym leader?", the plumber asked.

"Uh-huh", Sonic answers and shows him the badge." What about you?"

"I defeated him long before you."Mario said as he shows the blue blur his badge. "Hey since you're here let's have a battle to see who has improved."

Before Sonic could say a word he was cut off by a loud noise and a huge object flying high in the sky which amazed the two.

"What was that?!!", Exclaimed Sonic looking up in the sky.

" I don't know",Mario said also curious about it. "But it was kinda green and was flying very fast.

"Do you think it's a pokemon?",Sonic asked.

"Mabye.....Let's ask the professor",Mario said.

"Ok, let's go",Sonic said.

The two then make their way to the professor's lab.

To be continued...........