Well this is one of the strangest games I've played in a while. Something about it reminds me of Mario and Luigi Bowsers Inside Story. I'm not a big fan of Mario games generally, but both that game and this one have a similar charm, the way everything jiggles and bounces. Was this intentional.
Besides the game's feel, there are also interesting mechanics at play. Not being able to die but just change form is an interesting mechanic and the collecting different "friends" gives each level a feeling of progression. My first gripe is that I wasn't going "ah ha" as much as I was going "I guess that's what I do"; reason being that it's hard to keep track of what each thing does, more specifically their stats. For example, one puzzle I didn't know that Mr speedy couldn't jump as high as Mr plain block, I just kinda went "I guess he must jump higher because it's the only way to solve this" where as I could have been going "Aha, now I need Mr jumpy." Simply having a way to check each stat would fix this, though somehow I doubt you'd feel that would fit the game. A better approach then may be to A. have their designs better reflect their skills B. have more distinct skills. Perhaps rather than standard high jump, the block jumping higher could have a double jump, or some slight variant on a jump that helps it stand out in the players mind. The size mechanic is a good start.
My second quarrel is with what the game is. Is it a puzzle game, is it a platformer? No idea. The short answer is both but this always raises issues. One part faced me with multiple challenges that I had to keep redoing the first just to beat the second all the while trying to solve a puzzle. HOWEVER, except for maybe 1 or 2 examples where it can become a bit tedious, this isn't really a problem in this game since taking damage/"losing" doesn't reset the puzzle and only pushes you back a little whilst also acting as an augmentation to the puzzle rather than a straight loss. For the most part I think this game actually does a great job of blending puzzling and platforming, not very punishing and everything's on screen so I don't have to overcome platforming/navigation just to find out what I'm doing *cough* Iconoclasts *unconvincing cough*.
I do have some other gripes, the part where I had to wait for the timing to line up between the enemy and the falling block was annoying (FTR, this is the part I complained about earlier), and I'm not sure about the part where you have to jump up into the brown spewy to progress as I'm not really solving anything, yet when I solved it I did more so feel "oh that's cool" rather than frustrated. There's not much I can complain about without it turning positive which overall I think says all it needs to. This game feels childish in a strong sense, everything has googly eyes, it's creative, it's bouncy and energetic and half of it's "flaws" are more endearing than anything. With all that said, even in a kinda shitty mood I managed to enjoy this game which is impressive; so congratulations, you get the seal of approval from a random person on the internet.