Kamen Rider Decade and the Dark Rangers.

Kamen Rider, Chapter I

Chapter 1~

Tsukasa opened the door, not quite sure what he was expecting. A fan girl? Someone who could've sworn this was a coffee shop? He was not prepared for a teenager, badly bruised with a fade green t-shirt and damaged gi pants falling in his arms.
"Please, you have to help me before they come after me again. I need to...I need to rest..."
The stranger would then collapse. Curious, Tsukasa helps walking the stranger onto a couch. Tsukasa grins, remembering this is exactly what happened that one time with Kaito Daiki was in the World of Shinkenger and lost his gun. A monster from the World of Shinkenger had beaten him up quite badly with his own henshin device. Tsukasa would go prepare to make some tea, waiting for the stranger to recover. Suddenly, there was another rap at the door.

"Can't I get any peace here?" Sighing, he goes to answer the door, seeing some sort of teenager with a headband, wearing red standing in front of him.
"This isn't a coffee shop before you ask. This is a film photograph developing shop."
The teenager, looking smug, would push Tsukasa roughly. "Have you been harboring strangers in here? More in particular, a teen wearing green. He should be heavily beaten up." The teenager would smirk at saying that.
Tsukasa, annoyed at being pushed, flashes the camera directly into the teens face. "Yes. I just took a picture of him." The picture developed, Tsukasa would forcefully slam the picture into the teen's face.
The teenager would stagger back, falling off the stairs. "I hope you had a nice trip too. And no, I have not a clue of which you speak of. I haven't harbored any strangers here. I just traveled here. Remember that."
The teenager groaned. "I'll remember this." He would turn to his hang of friends wearing different colors.

"Guys, Tommy isn't here. Let's head back to Zedd." They take off. Tsukasa would close the door, looking at the stranger.
"Sou ka…" Tsukasa begins to piece things together, the knowledge of the world finally connecting with him. "This must be the world of the Dark Rangers. Or, more precisely, the world of the Dark Zyurangers. Or in this world, the Dark Mighty Morphin' Power Rangers. This means, that teenager I just talked to must be the Red Ranger. Who's now evil apparently. At least in this world."

The teenager, recovered, would stare at Tsukasa with a confused expression. "Who are you?"
Without skipping a beat, Tsukasa would answer smoothly, "The Destroyer of Worlds." The teen would get up, fall into a fighting position before wincing.
"Relax, Tommy, is it? I use that term loosely. If I wanted to destroy you, you wouldn't be here. It's a running gag. At least from where I'm from. Or where I go I should say. You know people still call me that? Even after I finished all that?" He sighs, shaking his head.

Tommy looked up at him. "How'd you know my name? Do you know what's going on in this moment right now?"
"I get the gist of it. And I just know that." Tsukasa would give him the tea he made. "It's specially made. Natsumi's special. It's made with herbs. At least I think its herbs. Knowing her, that could very well be poison. But it'll help you recover."
Tommy, hesitant, would take it. Taking a deep breath, he drinks it. He would begin to feel better.

"Thank you."
"Thank Natsumi. It's her secret formula. Just wondering, you would be the Green Ranger, yes? Which means, did Zordon give you your powers?"
Looking surprised, Tommy nods.
"Are your powers fading at all?"
"They've began to. How do you know this….?"
"Decade. Call me Decade. And I come from another dimension. Entirely actually. The Tommy I know was evil at first but he lost his powers after he turned good. So, what I think is that if the world is really flipped, you might be turned evil to your current good state. And when your power complete fails you, you'll become evil again. And I would say Zordon would be good guy alone?"
"You are actually wrong on that one bit. I was Zordon's student. I've always been Zordon's student. My powers are only weak because I've been in battle for too long. That and I've suffered damage multiple times without anytime to recuperate."
"I thought as the Green Ranger, you were capable of taking out the entire team easily?"
"I was. But then I hesitated. That cost me the war. As if Lord Zedd's army wasn't enough. Fighting the rangers AND his army is a lot of work. I don't think I can handle it myself."