With all the fan-made pairings in various Sentai shows, especially Dekaranger and Shinkenger, I think a girl with girl pairing, with Mako and Kotoha comes the closest to being "hinted upon," at least in Kotoha's mind. At least it is somewhat hinted in the recent Shinkenger V-cinema movie that Kotoha might have a bit of a crush on Mako.
For those who haven't seen the V-Cinema movie (Shinkenger Returns), the Shinkengers are trapped in a dream state in which they go from one illusion to the next. These "illusions" are based somewhat off of tv dramas and movies. In Kotoha's illusion, she disguises herself as a boy in order to attend an all boys school. The reason why is because she was in love with Shiraishi-kun (a.k.a. Mako, it's her surname). Mako in this scene is a boy, and Kotoha is about to "confess" her love for Mako, when Genta, Chiaki, Ryuunosuke, and Takeru reveal that they're also girls disguised as boys. If you haven't seen this scene and a little confused, in this scene everybody's gender is switched except for Kotoha's. Later on towards the end of this movie, it is somewhat hinted that these illusions may have been their "deepest desire." Especially when Ryuunosuke is questioned about his illusion. So that made me think, does Kotoha really have a crush on Mako and is afraid to admitt it? Maybe she feels guilty about having a crush on another girl, which may be why Mako is a boy in this scene. Kotoha has been known to have one-sided crushes before, particularly on Takeru and Chiaki.