Metal Fighter Miku

Both are mid-90s series about a group of girls (presumably sisters) who pioneer their way through new fields in society to reach the top and achieve their dreams. Cute side characters are sprinkled throughout along with a decent dose of silly and serious moments. Catchy J-pop songs, group dynamics about how to work as a team, discovering hidden secrets about the dark side of their work, and the influence of an outsider are prominent features in both series. They also have similar animation styles and character designs. 

Both shows have predominantly female casts who fight in sci-fi combat sports, with both shows having a heavy focus on the girls training and learning new techniques, while building up to a rematch against an opponent who defeated them in the beginning. 

Mahou Shoujo mixed with Mecha is a rare thing but these two anime are examples of such. Metal Fighter Miku has only transformation sequences while Ginga Ojousama Densetsu Yuna is Mahou Shoujo at its core with some elements of Mecha added in. 

Bubblegum Crisis inspired many series and Metal Fighter Miku is most likely one of them. Four main female characters - check Metal/Mecha suits - check Fighting sequences - check Cool soundtrack - check Be advised that Metal Fighter Miku is not as great as Bubblegum Crisis, but nonetheless it's still a really good series. 

- Both are sports anime featuring an ensemble main female cast. - Both series feature its female characters practicing a rougher sport that is considered "manly" within their stories. - Both series feature its cast slowly rising through the ranks to gain notorierity in their respective fields. - Both are anime released in the 90s and happen to have relatively similar visual styles. At least to me as I was watching these series, I found that both Metal Fighter Miku and Princess Nine embody the spirit of "girl power"; often found in some 90s media, both series felt like they were reflecting popular emerging ideals during the decade of their release. read more 

Futuristic, unusual competitive sport and main character growing into the role is what these two anime have in common. In Metal Fighter Miku it's Neo Pro-Wrestling - a version of pro-wrestling where fighters (all female) use metal suits. In Battle Athletess Daiundoukai it's a mix of futuristic versions of some well known sports (e.g. zero-G lacrosse).  

Our main heroine vows to beat the strongest wrestler in the world. One series takes place in the future while other does not. Sakura is an idol singer while Miku is a normal girl who loves wrestling. Sekai de Ichiban Tsuyoku Naritai has fan service + idols + wrestling while Metal Fighter Miku has no fan service. Both series depict the art of wrestling.