To clarify: up until the point that Prof. Tatsumi has his children reboard the Go Liners and use a ramp to launch it into the sky, it's not really clear why the Go Liner is flying in the intro. And then it combines in midair. And lands on some train rails. But the clincher is when it rolls up to the giant Saimas (two of them this week!)... and you see just how big it is compared to them. It doesn't trade blows with the Saimas so much as just blow them away.
The siblings' final stand against Grandiene, who's now taken over her resurrected and brainwashed sons, Zylpheeza and Salamandes.
Matoi: "I see... Dad believed in us without any doubt. That's why (he built) this robot..."
Nagare: "That's right. Which is why this time, it's our turn to believe."
Sho: "In Dad's robot!"
Daimon: "In our bond as a family!"
Matsuri: "In this planet's future shaped by people's lives!"
Matoi: "And... in ourselves! The power to believe itself is our bond!"
During the movie crossover with the Timerangers, the crowning of moment of awesome was made when the professor tells Go Red to call the Victory Robo. The awesome part comes when the Victory Robo shows up... from 1999! Of course since this is them just borrowing the Victory Robo from that time, they have to return it so in the end it is still destroyed. But for the time being it can exist in the present for about 3 minutes or else the temporal shift will cause the world to collapse.