For anyone who's already got the first speedup...Is it worth it, or does the stage require large coin investment?
First Speedup is worth it I'd say as you get coins every 10 stages after 50 anyhow. I used Mega Latias, Xerneas, Dragonite and Latios (all Maxed minus Latios whom is 5) with Attack Power, Disruption Delay, Mega Start and Time +10. I beat it with 27 seconds remaining so didn't need the Time +10 in the end, but the board could've been worse. The Metal Blocks are far worse than Goomy as a disruption.
Beyond that, I did 101 itemless with Mega Gardevoir, Latias, Dragonite and Latios. I only won with 10 seconds remaining which didn't feel good whatsoever.
After that I tried my Candy Maxed Mega Glalie on 102 and beat it with 20 Seconds remaining, so I'll probably stick with Mega Glalie. Mega Gardevoir really struggles now, since you need vertical matches to do anything, which is pretty impossible with all of the Metal Blocks taking over the entire board. Mega Glalie usually struggles with timed stages, but it actually cleared the blocks pretty well on this trial run. Could be a fluke though, so we'll see. My other Mega options aren't very good anyhow. Mega Latios is the next best option, but isn't Maxed, so damage will be reduced. Latias is maxed, but evolves so slow and Altaria is slow as well, plus pretty meh as I'd like more coverage throughout the entire board.
EDIT: Also for 100 and up: On the starting board, wherever there aren't Metal Blocks in the middle. move the Pokemon there up until you hit the bottom of the board for a nice start.
The default setup is like this where Metal Blocks will be one of the numbers while your Pokemon will be the rest. The Ms are always Metal Blocks.
11MM11
221122
332233
443344
554455
MM55MM
So in this setup, let's say the 5s are the Metal blocks, you'd want to move the 2s in the middle two columns up one row, then the 3s and then the 4s. That's six matches, so that should destroy the Metal Blocks too.
More info here if needed:
http://www.pkparaiso.com/shuffle/lista-de-fases/fases-especiales.php?lang=eng