Spike has re-used everythng Dimps did in the Budokai games (though usally in a more crappy way) from the Password System to the new teleport counters and sonic sway.
They're reusing 'ideas', but they all get their own little names and are presented as new things. They are, after all, additions to a completely different engine, even if based on what B3 did.
However, the assets that I was talking about are animations, cutscenes, 3d models, textures, etc. They scrapped everything from Budokai for Tenkaichi 1, but I don't see why they'd have done that if they could just reuse Budokai's, especially the textures and 3d models of the characters. If they could just reuse those, they wouldn't go out of their way to make new ones for everyone.
As I've said, they can include a Tenshinhan/Yamcha dance fusion, but it won't look exactly like Budokai 2's "Tiencha".
Though I retract my previous statement, he could still be called Tiencha, as that name probably was chosen by whoever was localizing the game.
