Luigia and Ho-oh are fine. There simplistic and they should stay that way.
Lugia - 3.9/5 - Can it's wings not be it's hands.
Ho-oh - 4.2/5 - It's a phoenix, what do you expect?
Groudon, Kyogre and Rayquaza are high on the design list for legends, not too over decorated nor bland. Same goes for Primal and Mega forms.
Groudon - 4.8/5 - It's Kiaju like design fits it really well.
Kyogre - 4.5/5 - An interesting and unique take for a whale.
Rayquaza - 5.0/5 - Perfect for a dragon.
Palkia and Dialga are complicated, mostly due to what they look like (Palkia) and not really representing anything natrual, but they don't really have a lot of stuff going on with them. Giratina is really the only good one here.
Palkia - 3.0/5 - It's back sprite, fix it.
Dialga - 3.8/5 It's facial area needs some work.
Giratina - 4.9/5 It's design fits it for the supposed satan of the Pokemon world.
Zekrom and Reshiram aren't really over-designed, there just... a bit bland. Zekrom looks a bit sleeker than Reshiram.
Kyurem is a yes, it's black and white forms as just make it worst.
Zekrom - 4.0/5 - It's design is sleek and simple.
Reshiram - 3.8/5 - Kind of bland but fits being the opposite of Zekrom.
Kyurem - 2.5/5 - Way to many things going on with it
Yveltal and Xerneas are alright, there a mixture between the weather trio and creation trio's design. You can tell what Xerneas is and Yveltal is.
Yveltal - 4/5 - It looks like a red eagle.
Xerneas - 4.2/5 Just plain majestic, it's a rainbow deer.
Solgaleo and Lunala are fine as well, their designs are solid and can tell what they represent as animals.
Necrozma normal form feels a bit blocky, to me it's not as bad as Kyurem though. I would put it below Solgaleo and Lunala design.
I wouldn't consider Necrozma light form over-designed, just a bit too spiky, it's design's okay for a alternate form and leader of the trio.
Sogaleo - 3.8/5 - It's a lion.
Lunala - 4.1/5 - It's majestic.
Necrozma - 3.7/5 - What I said.
