Depends on the number of lines. Level is equal to the number of tens of lines + 1, once we realize the initially chosen level (if we start at level 5 then we go to level 6 at line 60, if we start at 9 then we go from 10 to line 100), the speed increases with each level.
But I seem to have read that after a certain level it no longer accelerates. I never noticed, however, for my part, that I had not come far enough (I must have come in 20 years). 
+1. Furthermore, even just being in an emulator can allow you to do things that aren't necessarily possible with the original console, either because the emulator has slightly different behavior, or because it can contain bugs that would almost never appear under normal circumstances on the console. .
For example, I played it a lot simultaneously on an emulator on my phone, and it used to save the virtual controller state after a session, rather than “replaying” it every time. After a while, Tetris started systematically giving me squares.
On GB, the shuttle is when you finish in B mode (the mode where you start with pieces and holes already in place and where you have to do 25 lines to win) with high (the pieces and holes already in place) at max. In normal mode, they act as missiles, getting larger and larger by 100,000, 150,000, and 200,000 points.
On NES you have the shuttle in normal mode from 100,000 points (given the low levels, I assume the NES version probably gives less points):
At Max, Basile is definitely the one to get going 
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