Level 50... Giratina unclenches its paws to produce two shiny middle fingers. Ooh, boy, where do I begin?
Firstly, you start the board drowning in Shaymin. Yes, Shaymin of all things is your fifth mon (someone else attempted to see if it functioned like Regirock on the Regi stage; it does not, and you will end up with Spinda if you try to put Shaymin in your party). I don't think Sleep Charm works on Ghosts, so that means it pretty much is dead weight. At least it's neutral dead weight, I guess.
As soon as the stage begins, Giratina greets you with about 3 randomized barriers, and is then on a timer to wreck your face with disruptions every 3 turns after. Depending on how Giratina feels, this can be 5 random barriers, a random row of barriers, or a double disruption with some random barriers and a column of blocks. Actually, I haven't quite figured out if this is entirely random what Giratina chooses to do, but I highly suspect that Giratina punishes you for removing too many of its disruptions in a single 3-move interval. I feel like I got a lot more double disruptions the more I tried to clear the board. M-Banette cannot Mega Evolve quickly on its own under these conditions, so when I lost the first time, I swapped it out for M-Gengar. Gengar can get there quickly, but only being able to remove itself does nothing for your board if it's not trapped in barriers. So, this is probably a good time to whip out an all Ghost M-Banette team. If you don't have that, level 50 might be a good place to stop as I doubt you can do 50-100 itemless without an M-Banette Ghost team. I'm hoping I can do this itemless with one though.
Edit: All-Ghost didn't work out. Chandelure just doesn't pack enough punch, and I funded the majority of Banette's Mega off of Banette matches anyway. I think I'll switch back to my regular team, but swap out Yveltal for Absol. 4-6 turns without a disruption would be amazing on this stage.
2nd Edit: Giratina's disruptions are 100% random. My fourth attempt was over before it even began, as it immediately put down a column of blocks at the start of the match. Doing this itemless is going to be a challenge. Which is fine, I guess. I did kind of coast through the first 49 levels... but I need to know if I can crack the code to doing this itemless because it sets the tone for whether the next 50 levels are worth doing. If I can handle it now, then all I'd need for the tougher levels is maybe a Moves + 5. As far as I'm concerned, 40,000 easily replenishable coins (50 Moves +5) are definitely worth a permanent Mega Speedup for a Pokemon of my choice.