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Some of the stuff you describe reminds me of elements of Samurai Pizza Cats
https://www.youtube.com/watch?v=bXiJYcK4-GU
But also Mon Colle Knights
https://www.youtube.com/watch?v=XaEJzQeZaDs
But the underground tunnel thing is a pretty common trope. I think the Thunderbirds popularized it (it was just a simple way to get puppets from one place to the other :p) and even Batman '66 to some extant. Old Go Nagai shows like UFO Robot Grendizer use it even.
Not anime, but Code Lyoko?
Fighting Foodons?
I think it had a young boy and a girl who used to work at a restaurant (not sure), they had superhero robot suits that they changed into while going through these underground tunnels. They used to be launched into the air, ive tried searching for about three hours now. It was something similar to Mega Man in appearance.