Heya ^^ I had some ideas about Yveltal, Xerneas and Zygarde :3
About Yveltal, I think she should be hyper hourglass and dominant. Not in a mean or harsh way, in a playful and "nice" way. She love to find the weak points of her mates and overuse them until they almost pass out from exaustion. She always try to rise the number of times she made her mates cum in a row. She love to praise the girls about her shapes (she would tease Zekrom about lactation and will help Lugia shove as many dildos in her ass as she can) and sexiness, and in a less lewd way if someone doubt of don't feel too good she will cheer them up and help them. She is very lively, she would be the kind of person who will drink all the alcohol in the party just because she think it would be fun to do so. About her passive aura it would be cool to link it to cumming. When she cum, and she cum easily, she grow taller and when she make other cum she become curvier (she often become immobile because of that), but the changes last one hour at most but stack. About her signature move, oblivion wings, it can have an effet that will not be harmful at all for the target but will have other effects : she will drain their fertility and attribute. The fertility drained will come back to the target within the day but will boost permanently Yveltal's fertility and the stolen attributes will not affect the target but Yveltal will temporarly have them (if she steal the attributes of Lugia her ass will become humongous, extremly sensitive and way more fuckable). Oh, and because she can grow taller I think she should be a bit smaller than usual. Not as small as Mew, Manaphy, Celebi etc but a head shorter than "regular" size. Basically, being at the good size for having her head at the level of Mewtwo's boobs :3
About Xerneas, I think she should be curveless and submissive. Not shy but she just love letting others use her like they want to have their fun, as long as she enjoy it too. She's kind and love to help, but if you want to reward her she only accept lewd rewards ! She's not as much of a slut as Yveltal, contrary to her she prefer arousal than cumming. She love to tease, arouse, drive mad with lust people around her, and by doing so she almost always give powerful orgasms. Yveltal's own challenge is to always increase the number of orgasms she can give to each person in a row, Xerneas' own challenge is to give the stronger orgasm possible to each person. About her aura, it should be linked to arousal. When she's aroused she shrink progressively and when she arouse other their curves swell progressively (yes, not her curves you'll see why). The persons she love to arouse the most, beside the MC (BTW she can make the MC's cock grow without him changing his cock because of that), are the ones with the less curves because she just love too much seing them go from curveless to properly massive, and if they end up immobile it's just a nice bonus. Geomancy can have an other effect, it can give her any shape she want. She can even become a futa or totally gender swap, so she can be a femboy or else, she can become a massive milf or a cute critter etc, but it's only shape, she can't look like someone else. The modifications are not instant so her forms progressively change to what shapes she chose. The only thing is that when she use it it permantly increase her fertility. And because she can shrink I think she should be a head highter than normal sized person. So Mewtwo's mouth would be at the same level that her nipples :3
About Zygarde I think she should be a massively muscular for showing her strengh and massively hourglass for showing her evenness (I don't know if that's a word, but her will to make everything even, in control). If you make her have multiple forms it could be fun if the more complete she is the bigger she become. Her mental will evolve a bit so I will speak about it a bit later. About her aura being an opposite one, I think that it could be cool if this aura boost the opposite of the attribute of each. For exemple for Lugia it grow her boobs, for the MC it make them turn into a futa, for an hourglass it make them have a bigger belly, someone small will grow etc. I think that using a bit of how work both auras of Yveltal and Xerneas will be nice, so when her or her mate feel sexual pleasure it affect her mate and if her or her mate cum it affect her. The effect on her like she's muscular and hourglass should be making her fatter :3 And of course this modifications are temporary. About her special move having an other effect, she have a lot but I had an idea about core enforcer. It can have an other effect that can change the body of other to the shape she want. Basically it's like Geomancy from Xerneas but used on other ^^ But it have two other effects, firstly it will permanently boost her fertility but the target will have a change of mind fitting the change until the effects stop working, but based too on the mind of the target. So if she use it on Lugia for making her boobs enormous like she's a huge butt slut she will become a huge boobs slut. I have an other idea for an other signature move of her, I think thousand arrows could have that, to temporarly swap two people's form. So if she use it on herself and the MC she will have the body of the MC and the MC the body of Zygarde, if she use it on mew and mewtwo they will each have the body of the other etc. It's not that their mind change body, it's that their body change so if someone is pregnant their belly can't shrink but if they are not or less their belly will swell just because it's the shape of the other. Doing that will too give full access to each other's memories the time of the swapping, tastes, thoughs, plans and kinks included.
So, now that we spoke about the girls I may speak about the plot idea that I got ! So, all three are virgin before the MC shows up. Yes, I described two of them as sex addict (mostly Yveltal but Xerneas still love it) but it can be explained by the fact that they was sexually frustrated. Zygarde think that evry thing should be kept in control, that everyone have a purpose and should stick to it. That always make her hate her aura and capacities who do the exact opposite of this. She threatened Yveltal and Xerneas to never mate because it would make multiple gods of death and life, that would put everything out of control. Yveltal's plan was to make herself the most fertile she can and find an extremly fertile mate because she's greedy but too because that would give her an excuse to Zygarde : two persons so fertile should reproduce, it would go against natural order to not do so ! In truth, it would not convince Zygarde but Yveltal was mostly doing that to use Zygarde's own logic against her. For Xerneas she was very sad to not be able to give life herself so she managed her frustration by arousing people without mating (she always got tempted to let people cum on her but she was afraid that Zygarde would see that as a try to get pregnant without looking like she's doing so). Beside that, Zygarde lied to them to make them think each other hate each other, so Yveltal and Xerneas got in conflict, but when the MC will catch them, and breed them, they will agree to put their grudges aside for helping their master capture Zygarde too. Zygarde don't like the MC because with all the breeding she's done a lot of godesses will multiply and, for her, it's an apocalyptic thing ! But she knew that if she go to the MC to stop him she should face a lot of the most powerful beings on the planet so she let him came to her, but didn't expected that he took Yveltal and Xerneas (it could be cool if he didn't plan on taking them but they begged for it so he accepted). The fight against Zygarde showed up that the hatred between the two godesses was just a manipulation from her so they team up to take revenge on Zygarde : Yveltal drain her energy with the main effect of oblivious wings and Xerneas will drastically boost Zygarde's fertility (she's the godess of life, I think she can do that so ^^) so she's all ready for the MC to breed. After the breeding, the MC will tell to Zygarde that her role is not necessarly make things stay like they are but more to adjust things so they never get too much on one side and not enough on the other, and that not breeding the legends will make their specie to risk to go extinct. That give her a new purpose and she's glad that her new master helped her. The two other legends want to keep their vengence on her for what she's done to them but the MC will tell them that after stopping their conflict it would be too bad to start a new one beside they are all in your harem so they should start getting along ! They accept and will even become friendly when they will learn each other after ^^
I think that they should be the most fertile of all, being the size of someone about to give birth when they just got impregnated and being almost immobilised by their size when they are about to give birth.
I thinked on some downtime events ! I think Yveltal and Mew could really become close friend, being lively and size queens both. For one downtime event the MC come back from somewhere (from shopping ?) and see Yveltal being absolutly gigantic, taller than any tower, mountain sized ! And she keep figering herself to make her grow even taller !! She have Mew on one of her hand. The MC ask her to stop or he will make her come back to her ball but she tease the MC, saying that he's loving what he's seeing and that she do that mostly for Mew. He finally accept to ler her have her fun and Yveltal ask to bring Latios. That's done and Yveltal use oblivion wings on her so she steal her attribute : being a futa (using oblivion wings this way don't hurt at all the target). Of course her Yveltal's cock is the biggest cock Mew saw so she lust over it and she take it in her pussy (we already saw that she can modify her so her eggs are safe). They fuck like that, Mew looking like a condom on this cock, and each time Yveltal cum it bloat Mew's belly to an extrem point. She switch from pussy to ass at one time so Mew vomit cum. It end when the effect of oblivion wings stop. Mew feel Yveltal's cock shrink but don't want it to stop. Yveltal want to please Mew the most possible so she put her shrinking but still massive cock on Mew's face so she can worship it until it's fully gone.
An other downtime even I though of is to have one where the MC ask to Jirachi if other girls had wished she granted and we will have some choices of pokémon, for the Yveltal part she asked Jirachi to have a trigger that boost temporarly so much her milk production that it force her boobs to lactate a lot for the whole time it's effective.
I think of some events in the boat between Kalos and Alola. One where the MC asked what dreams she give to her girls and it will have an Yveltal and Mew part. In itshe explained that both of them asked to have linked lucid dreams when they are both asleep and let them remember them when they wake up. Cresselia say that when she lookin their shared dreams she see that they try kinks that would be impossible to do in real life, experiment new things and even one time she catched them training for a prank they did after they woke up. The other even in the boat that I thinked of was again between Mew and Yveltal. Mew and Yveltal took their master in an empty chamber and tease him, but Mew have the exact same shapes as Yveltal when Yveltal get curvier or taller Mew copy the changes ! It end up when both completly fill the chamber and that the MC is pressed between the two girls.
I have others ideas, but not anymore with Yveltal (except one that will show that the three aura girls became friends but I have no precise idea for that).
It could be cool a downtime event where Zygarde propose to swap the body of two members of her harem. It could have Mew and Mewtwo but I have no idea about what doing in, it could have the MC with a girl (with Zygarde ?), but what gave me the idea was mostly Groudon and Kyogre. It could be fun if they swap bodies and have full access to each other memories, kinks, secrets and all :3 It could maybe even make them s that they have a lot in common and, on the demand of their master, will start to do things they both enjoy then will not stop until they transform back ? That could make them go from pure hate to "friendly" rivalry ? :3 I had other ideas with Zygarde, like getting inspiration from the MC's words when he tamed her and want to make other girls try different, complementary shapes and one where she boost a lot different girls's attribute (Making Lugia's ass even bigge, more sensitive and stretchier for exemple).
I thinked of an other downtime event, this time with Xerneas. She want totry being overwhelmed by a cock, so she ask her master to grow his cock to wailord and will worship it. The more she worship his cock the smaller she will become until being extremly small, even Mew would look like a giant compared to her. She will then impale her ass on the wailor's cock and be used as a condom, except that she will vomit cum ^^
SO ! I know it is VERY long and all, but I had a lot of ideas and wanted to share x3 I hope that it will please you, and that inspire you :3 Tell me what you thinked of it ^^
