When combining art styles, study the key elements of each. In Birdy the Mighty Decode, there are often dynamic poses and a sense of movement. In the other franchise, there might be a focus on detailed backgrounds or unique character expressions. Try to merge these elements. So, if the other franchise has great facial expressions, give the Birdy characters some of those nuances while keeping their own distinct body language.
One way is to use color as a unifying factor. If the other franchise has a distinct color palette, try to incorporate some of those colors into the Birdy the Mighty Decode characters in a way that doesn't look out of place. Maybe use shading techniques from both art styles to create a new, hybrid look. For instance, if the crossover is with an anime that has a lot of pastel colors, add some pastel accents to the Birdy characters.
Well, you could start by taking the more angular and sleek design of Birdy the Mighty Decode characters and blend them with the softer, more fluid lines of the other crossover franchise's art style. For example, if it's a crossover with a more cutesy anime, you might soften the edges of Birdy's mecha slightly while still maintaining its overall shape.
One interesting plot idea could be a crossover with another popular anime where the characters from Birdy the Mighty Decode have to team up with the new characters to face a common enemy. For example, if they cross over with Naruto, Birdy and her allies could join forces with Naruto and his friends to battle a powerful alien threat that is too much for either group alone.
The art styles could be combined by having the characters keep their distinct looks but interact with environments that blend both styles. For example, Cuphead and Mugman could be running through a hall in the Batim studio that has the dark, inky look of Batim but with Cuphead - style geometric patterns on the walls.
You could have the characters from Undertale drawn in a more FNAF - like style. For example, make Sans' eyes glow like the animatronics' in FNAF. Or give Frisk a more robotic look while still maintaining their Undertale charm. The backgrounds in the fanfiction could also be a blend. The colorful and somewhat cartoony Underground of Undertale could be made darker and more spooky like the FNAF settings, with broken animatronic parts scattered around.
One idea could be to crossover Birdy with a popular mecha anime. Picture Birdy in a Gundam-like universe, fighting side by side with giant robots. Another could be a crossover with a magical girl anime, where Birdy has to learn some new magical powers to save the day. Or perhaps a crossover with a detective anime, and Birdy uses her skills to solve complex mysteries in a new setting.
The art styles can be combined by taking the detailed, gritty textures from Wolfenstein and applying them to RWBY's more anime - inspired character designs. For example, the characters' clothing could have the worn - out look of Wolfenstein while still maintaining RWBY's unique color schemes.
Some excellent characters for Birdy the Mighty Crossover fanfiction are Lelouch from Code Geass. His strategic mind and his complex personality would add depth to the story when combined with Birdy. Also, Asuna from Sword Art Online. Her combat skills in a virtual world and her strong will could lead to great team - up moments with Birdy. And don't forget about Ichigo from Bleach. His ability to see spirits and his powerful sword - fighting skills could make for some exciting crossovers with Birdy in different scenarios.
When crossing over with something like Sailor Moon, which has a very feminine and colorful art style. You might show the Yamato crew in the magical world of Sailor Moon. The Yamato itself could be given some of the glittery, magical elements of the Sailor Moon art style while still maintaining its own hard - edged look. For the characters, the more military - style uniforms of the Yamato crew could be combined with the frilly outfits of Sailor Moon characters in some unique ways.
Well, the bright and colorful style of My Little Pony can be blended with the more detailed and sometimes more realistic art of Disney. For example, the soft, rounded shapes of the ponies could be placed in a Disney - like landscape. The big eyes of the ponies could be adjusted a bit to fit the overall look when combined with Disney characters.
The art style could be a blend of the dark and gritty look of Watchmen with the more colorful and heroic style of DC. For example, in scenes where the two universes collide, the backgrounds might have the gloomy, rain - soaked look of Watchmen's cityscapes, while the characters from DC retain their bright costumes and heroic stances.
Well, without reading the actual 'birdy the mighty naked fanfic', it's hard to say precisely. It could be a fan - created story that delves into the deeper emotions and experiences of the characters in the 'Birdy the Mighty' series. Maybe it looks at how the characters react when stripped of their usual defenses or status, in a more symbolic sense of the word 'naked', and then takes them on a journey that is unique to this fan - made narrative.