Both shows entrust the lead characters with a figure/gun of a blue-haired anime girl that transports them into an alternate reality where they must then fight. But as things progress, things are actually more real than they seem.
Both are shows about sentai otaku. Only Akibaranger is more exaggerated and played for comedy while Tokusatsu Gagaga is more realistic and slice of life.
Both deal with how Tokusatsu is made. Machi Action deals with it in a more serious manner while Akibaranger is more of a parody of Super Sentai with bits of how it's made sprinkled in.