Regigigas is mine just straight up because of its ability. Like yeah he has 160 base attack but you know what mega rayquaza has? 180 and no trade offs too for those higher stats.

Even in Legends Arceus did they give this pokemon an ability when there are no abilities in the game. Just all this stuff makes me not like it even if it was the only legendary I could get.

My least favorite is Cosmog, it's stupid that it evolves, what ever happened to Legendary Pokémon not being able to evolve?

Regigigas is definitely the most annoying for battling purposes. From a sprite design perspective, though, Enamorus is my least favorite.

Dauntez : Valid point. I agree. Same could be said about Kubfu / Urshifu too, and Type: Null / Silvally.

Dauntez : Arguably lore reasons Cosmog and group aren't legends. They are Ultra Beasts. Which ingame yeah legendary but lore they are normal pokemon.

Enamorus without a doubt I hated catching that mon with a burning passion I think my game was glitched or something I remember no one else having the issue I did when trying to catch it.

For me, Regigigas (for the reasons already mentioned), Phione, Keldeo, Virizon (which my phone always wants to correct to "Verizon" at least half a dozen times, lol), and Enamorous, are among some of the lamest legendary Pokémon either because of their ugly design, underwhelming stats and abilities, or all of the above. The Gen 4 remakes were definitely a missed opportunity to fix Regigigas either by way of a new form or at least a new ability, but instead, Regigigas was left untouched and remains crippled by the worst ability in existence.

For me, Regigigas (for the reasons already mentioned), Phione, Keldeo, Virizon (which my phone always wants to correct to "Verizon" at least half a dozen times, lol), and Enamorous, are among some of the lamest legendary Pokémon either because of their ugly design, underwhelming stats and abilities, or all of the above. The Gen 4 remakes were definitely a missed opportunity to fix Regigigas either by way of a new form or at least a new ability, but instead, Regigigas was left untouched and remains crippled by the worst ability in existence.

Preface by saying that any Pokemon officially classified as a 'Mythical' is just another legendary to me. Same with ultra beasts by the way. I will actually fight people over this opinion. From each generation:

Gen 1 - Moltres, it's got the same typing as Charizard, looks a lot lamer than the other two birds and you can't find it until the end of the game by which point most people will have an Arcanine or Ninetales anyway.

Gen 2 - Celebi, I've never liked this thing's design. Some weird onion thing with antennae and a terrible typing. Next.

Gen 3 - This was hard as I like all of these but I'll go with Registeel. I always kind of viewed him as the leader of the regis (before regigigas came in the picture) and he just didn't feel like he lived up to the hype of the other two. He also had by far the lamest role in the Lucario movie.

Gen 4 - Palkia man, that thing looks weird. It to this day still frustrates me that it is a water type? Why not psychic, aka the type related to space? This thing and Lugia should have swapped types lol.

Gen 5 - What on earth is a Virizion and why does it think it can hang with Cobalion and Terrakion?

Gen 6 - I've never particularly cared for Diancie. I don't hate it like some others but it's just boring.

Gen 7 - This gen had two. Silvally is lame, uninspired and ultimately pointless in battle. Zeraora is another pokemon I just don't care about at all, I think it looks stupid. There are so many good monkey pokemon and this thing fails at it.

Gen 8 - Calyrex. It looks stupid and has Celebi's crappy typing. The combined forms are cool mainly because of the horses, not Calyrex.

Gen 9 - Munkidori. I don't like this trio in general but at least the other two have something going for them. This thing just looks... weird.

I don't really care for a lot of the legendaries that have come from DLC for any of the applicable gens, but that could be in part due to a lack of exposure as I haven't played any DLC for gen 8 or 9.

If I had to pick one for a gen that I actually do have exposure to... I don't really care for the Gen 5 horse legendaries, especially Terrakion and Virizion. Cobalion is fine though and I do like Keldeo (mythical).