I do want to note that I think Dance Dance Revolution Mario Mix doesn't actually include any characters from DDR so I don't think there's any connection to the main franchise as far as I know. It's similar to Hyrule Warriors taking the gameplay of Dynasty Warriors and not actually being a crossover really.
For Tetris you could include Tetris Worlds and Tetris Effect (Tetris Worlds is about alien Tetris pieces and Tetris Effect gets into like spiritualism type lore iirc) maybe, it's one of the only Tetris games with a story, although it doesn't have Nintendo characters so idk if you'd include them.
There's also Puyo Puyo Tetris, which is part of the Puyo Puyo series, but Puyo Puyo is kind of its own beast and again is just using the Tetris gameplay for one entry in the series (plus Puyo Puyo is a spin off of an RPG series) and owned by sega