It's entirely possible to reach the score cap of 9,999,999 points on the final song of the second game. Pinball Scoring to it's logical extreme.
Let's talk about some of the songs, shall we? The final song of the first game, "Ready Steady Go", deserves a mention: all of the people who you previously helped throughout the game (with the exception of Ishida Tetsu and Cleopatra) come Back for the Finale and gather together with all the people of not just Japan, but the entire EARTH, to stop a meteor from wiping out all of mankind using a Combined Energy Attack formed from the power of cheering. The song is challenging enough that you really feel good if you do well on it, and the scenes of all the people from all over the world cheering, their energy auras getting bigger and bigger, will be sure to pump you up, and the "PLEASE! TRUST ME!" at the end can sort of be vaguely interpreted as a congratulations for making it through the song if you stretch your imagination a bit.
"Taisetsu na Mono" from the first game also. Nowhere else in the history of mankind has an election been so badass and Hot-Blooded, with the two candidates doing everything (up to and including ramming each other off the road) to secure the public vote, set to one of the most high-energy songs in the entire game.
In "Guts da ze!!", the horse (who has only won 1 out of 49 races in his history) comes up from dead last to first place in the final stretch. But that's just the beginning - the horse then proceeds to throw off its rider and chase down the thief all on its own.
The final stage of the second game. Just... seriously. The sun's activity stops, causing a rain of ice meteors that destroys the entire world and begins a new Ice Age. This is before the stage even STARTS. The people of Earth find a glimmer of hope as both Ouendan teams show up, putting aside their differences and working together to help the people, set to "Countdown" by HYDE. However, the song cuts out halfway through as the red Ouendan team performs a Heroic Sacrifice, pushing the blue team out of the way of an oncoming meteor. As everyone sits in shocked silence at what just happened, Takaya - the little boy from "Bambina" - feels something stirring in his mind, and begins cheering: "Ou-en-daan! Ou-en-daan!" Inspired, the rest of the people begin cheering along with him, as well as the blue team, resulting in the red team breaking out of the ice, revived by everyone's cheers. With "Sekai wa Sore o Ai to Yobundaze" by Sambomaster backing them, the two teams and the entire population of Earth cheer with all their hearts to restore Earth to its green and beautiful state and restart the sun's activity. The repeated screaming of "LOVE AND PEACE! LOVE AND PEACE!" at the end of the song will bring tears of joy to your eyes.