The first two seem a bit like fortress and archbishop. All four of them have their own strengths and weaknesses, as the first two are not weak to kingmovers while the last two are. In general I do feel the first set of two is quite a bit stronger, although the 2nd two have an unblockable the first two can attack around more and are much safer due to their kingmove.

moltress: This unit can be used to control the center of the board very easily, Although it has some weak spots, its path is NOT limited to just attack like fortress/archbishop giving it a lot more power. It can easily move very far in a matter of turns. I would say 17 cost, as the kingmove and the move-and-attack of the paths make it quite powerful even without the middle attack Along with that the move squares on normal fortress those allow a unit to block the path, making this much stronger.... As a fire bird why no magic destroy or create fireball?

arcticuno: Diagonals in my opinion are weaker than straights, many things can easily get by them and the diagonals themselves are color locked. This units new attack squares also allow it to kill things blocking the paths. As with fortress and archbishop I think it deserves to be 1 less cost at 16... as an ice bird, why no freeze?

zapdos: It can be powerful due to the path taking on the power of the unblock able, however without kingmove it is a bit weaker due to that weakness It can still attack where things are blocking it, especially since those are unblockables. As its a lot easier to kill this unit I feel 14 or even 13 cost.... as a thunder bird why no lightning

swanna? theres no legendary water pokemon bird: Same logic with the first set, the diagonals basically anti-color-lock this unit, when its on white it has to move to black. That makes it much weaker due to the lack of moves so I would even go for 12. Also if its a water bird... why no waterelemental magic squares?