I ended up switching out M-Altaria for M-Latias in the mid-140s. The good news about getting past 149 is that, excluding 150 and 191-200, you should not need to use any items. 151-190 is much easier than 141-149. Currently at 164.
Projected expenditures (assuming no failed attempts with items and basing item usage off of its effective cost, regardless of whether or not a free item is used)
Level 50: Can be done itemless, but you can save yourself some uncertainty with Time+10 and DD or just a single Attack+. (0, 2300, or 3000)
Level 100: Can be feasibly done itemless, but I'd recommend the trio or at the very least Attack+ to remove doubt since you shouldn't need to spend coins for 50 more levels. (0, 3000 or 5300)
Levels 141-149: You really don't need items here, but if you just want to get this over with, Time+10 is all you need. Personally, I only used one on level 149 to jump to 150 without issue. Either way, if you can clear one itemless, you can clear them all--the health doesn't increase for these 9 levels. (0-7200)
Level 150: Attack+ at the minimum, but I'd recommend the trio all the same. (3000 or 5300)
Levels 191-198: Attack+ is all you need, and you do need it (19k HP minimum). (24000)
Levels 199-200: The trio is all you need. Some may desire to use Mega Start for insurance, but these levels literally only have 2000 more HP than level 150. (10600 or 14600)
At no time is Complexity-1 necessary or even tempting to use for this escalation (if you're struggling with the blocks, it's more from the disruptions than the skyfall).
At most, assuming you used Time+10 on all levels from 141-149, the ceiling of this escalation's costs should be 59,400, with the bare minimum being 37,600. Either way, this is one of the most cost-efficient escalation battles in terms of coins spent per speedup. I think only Latias and Darkrai have it beat in that regard, and that's only if you spend closer to the maximum.
Also, keep in mind that successfully clearing all 200 levels will net you a buffer of 17000 from the coins alone, which does not factor in the free items obtained.
TL;DR: Do not be intimidated by this escalation being timed. If you are at least average at timed stages, this is definitely doable, with some item finesse required here and there, but not too much. We've definitely had worse escalations in the past.
Edit: Finished 199 and 200 with 15 secs and 21 secs respectively, using DD, Attack+ and Time+10. Essentially, it means you don't need Time+10 for this, but eh, it's the last two levels, so why not? Mega Start and Complexity definitely not necessary. In any case, 30 speedups released, 30 speedups obtained. Come at me, M-Steelix.
