ROTF Mixmaster. After doing a photo set for that guy (the G1 repaint), I never want to look at that figure again. In fact, I sold the set off because of him. Most painful transformation sequence between molds I've ever experienced. Robot is awful, anyway.
I think that was the idea. I still like deluxe ROTF Skids and Mudz a lot. Complex figures, but they've got everything figured out.
Alternators Battle Ravage - Not so much the actual transformation as a whole, but I just want to smack the person who decided where the door hinges went. Did they HAVE to go right where the hood panels need to lock into position and so make it necessary to use far too much force than should be required? I always fear I'm going to break the figure when I have to form the hood, and I haven't transformed Battle Ravage for about a year now because of it. Alt. Skids - Ugh. Great figure, but trying to get his head/hood assemblies to lock together in the right position is a nightmare because they can connect in SO many different ways. ROTF Stratosphere - here it's not the transformation, it's what the transformation DOES to the figure that scares me. With my figure, the amount of friction needed to force transformation into plane mode in the lower legs has actually caused hairline cracks in the joints, so I've not transformed him since. And I have to throw my vote in for the WfC Bumblebee/Cliffjumper mold as well. Not ONCE have I managed to get that damn alt. mode perfectly fitting together. I have to force everything because the tolerances just suck and I always have trouble getting the feet to fit under the backpack. At least robot mode is good, it's the only reason why I bought the toy really, so I could have a Classics CJ stand-in.
Alt Grimlock/Wheeljack made me frustrated the first few times. MP Megatron looks to be a pain, but I have no desire to try it, an oversized gun has no interest for me. Haven't tried my MP9 Rodimus yet, one day though. Big Convoy was a pain the first time as well, but he's easy after doing it once.
Prime & Jetfire were fairly easy for me... However... I think the one tha drove me insane was Generations Blurr/Drift going from bot to car... Couldn't get their sheaths/door pieces to sit flush with the rest of the car for the longest... Finally figured out that there was an order of how to do things to get them to sit flush... I'm extremely knit-picky and have this extreme taste for perfection in terms of looks for Transformers... As soon as I figured it out... I was extremely pleased lol
I'm going to with ROTF Mixmaster. I always either have to pull up pics, or watch videos to remember how to get everything to line up.
RID Megatron/Galvatron. I never transformed him, but my old roommate did. Took him a few hours to do all 10 modes. I'm not willing to but that much time or effort into transforming a TF. It's usually something I do when bored or on the phone to keep my hands busy.
I love transforming Buster Prime and Mixmaster - slow and steady. What trips me up is getting Altenators Shockwave's head lined up and angled correctly to go through the hood correctly without losing paint from his horns (or whatever is on his head) and still keeping the hood in place...
HftD Ironhide can be tricky the first few times. Took me a while to figure out exactly how those chest pieces tab in. He ended up becoming one of my favorite figures, though. Other than that, I'm usually pretty good at figuring out transformations. I didn't even need to look at the instructions the first time I transformed Battle Blades Prime.
I would say battle blades bumblebee is a pain since his leg transformation is a pain and remembering too turn his "arm guards" is annoying.
Yeah, I tried to close those in the body piece, then when I turned him back into a robot, those dreads were partway broken off.
well hes not a transformer character but a transformer crossover and that would be deathstar - darthvader. i've transformed him once and that was enough!
My two most frustrating transformations are on ROTF figures: Leader Prime and Voyager Mixmaster. I love the robot and alt modes on both figures but getting from one to the other drives me insane.
Voyager Mixmaster wins for me. I had Leader Prime figured out before him. I could get everything but the damn legs. Now I know it, but I really just hated it at first. I don't have a specific one, but any alt mode that is fully locked down. I don't usually use instructions when I open it up, and when I can't find a nice, easy panel to slide out of the way to begin the transformation, I get frustrated. Makes me feel like I'm going to break something...
For me it's anything with gold plastic. Not because of difficulty, but because they're all living on borrowed time. I love to transform my G2 Pyro from the UK... But one day, that waist IS gonna snap.
Freaking Beast Wars Tripredacus, mostly because of Ram Horn. Never did figure him out. But, he's in good shape, so I'd be willing to give him a shot. And don't get me started on Beast Machines Nightscream. He's in three different storage tubs right now. That damn toy does NOT do the character justice.