How they first met: They met when Ash first visited Sinnoh. Paul was a surly 14 year old challenging the Sinnoh League for the first time and Ash was a cheerful 19 year old wandering trainer. As Ash never traveled with Dawn in this AU, he and Paul just happened to meet in Hearthome City and Paul decided that challenging this older trainer would be a good warm up before he took on Fantina. It was an intense battle but it didn’t go well for Paul. After he won, Ash tried to give some advice to Paul, but the younger trainer just brushed him off, leaving Ash confused and concerned for the very moody teen. They saw each other a few more times later on after Ash befriends Dawn (who in this AU is a direct rival of Paul’s) but most meetings were pretty similar. They don’t actually end up properly getting to know each other until Ash returns to Sinnoh over a decade later.
Where their first date was: They had their first date about four months after Ash returns to Sinnoh. Prior to this, the two had been spending a good amount of time together since Ash had started babysitting Emery while Paul was busy with his Elite Four job. Over time, they began to develop feelings for each other, but it took a while for either to actually act on those feelings. Ash was the one to ask Paul out, just for a simple dinner out, but he was so nervous during the meal he kept making increasingly awkward small-talk in the hopes of trying to bond further with Paul. Meanwhile Paul was pulling the silent treatment because he was too busy trying to figure out if he had feelings for Ash or not. It was an awkward first date for sure, but it was the first step in their relationship and they now look back on it with embarrassed but fond memories.
When they had their first kiss: They had their first kiss on their fifth date, about three months or so after their awkward first date. They were walking home from catching a classical music concert in Sunnyshore (Paul’s idea, Ash discovered he actually really liked certain kinds of classical music after that). It was evening and gently snowing, the streetlamps casting everything in a golden glow. There were a few other couples out and about all huddled close to each other and Ash felt a bit left out so he sidled up close to Paul and linked their arms together. When Paul didn’t seem to mind they walked like that a bit further until they were at the point they usually split up to return to their own houses. Ash moved to unlink his arm from Paul’s, but the other man hesitated, so, without really thinking, Ash leaned in for a kiss and Paul reciprocated. They stood there in a bit of awkward silence afterwords before Ash made some vague ‘Catch you later, haha!’ farewell and headed off.
Who cooks: Both are pretty good cooks, but have different styles, so the agreement is whoever is home and able to cook, cooks. Since Paul has the busier job and the longer commute, Ash usually cooks. He learned to cook on the road (Brock taught him the basics) and picked up a lot of different recipes from around the world on his travels, so his meals are always eclectic and sound like they might be weird but end up being really tasty. They have a regular ‘Kantonian Takeout’ night each week though as Ash can get homesick for his home region’s food.
Who proposed: Paul, about a year and a half after they started dating on Emery’s 6th birthday. She had wanted her dad and his boyfriend to get married for a while now, so after she had opened all her presents, Paul handed her one last card. On the card was written, “As a special treat for the birthday girl, a little Starly told me she wanted her parents to be together for ever.” Right after she finished reading the note out loud, Paul got down on one knee and popped the question. Emery still considers it her best birthday present ever. (It turned out later that Reggie had helped his little brother come up with the idea.) 
The dominate one: Ash is the more flexible of the two, so he usually ends up going with Paul’s lead since he’d be fine either way, but he has some things he’s quite stubborn about that he won’t comprise on. So Paul is usually more dominant in that he’s the one making decisions, but Ash is one of the few who can get Paul to do what he wants so it’s a bit of a tossup. 
Their favorite pastime together: Paul still likes to test his skills against Ash in pokémon battles, though he’s a lot better at taking criticism and advice now than when he was younger. After they have a battle, or if they don’t feel like battling, they like to spend time with and take care of their pokémon together. Their teams have grown very close over the years so their pokémon are just as much family as their kids are. Otherwise, they might team up at the Battle Frontier or catch an evening show in Jubilife (which is where Ash works at the Trainer School.) 
Who kissed who first: Ash initiated the kiss, but they kissed each other at the same time.
Who is the flirt: Neither of them are very flirty, but sometimes Ash likes to try out cheesy or silly pick up lines to see if he can get a reaction from Paul. He considers his flirting a success if he gets a laugh out of his husband.
Who is the romantic: Paul is the more romantic one, but only by a little margin. He’s, perhaps surprisingly, very heartfelt and gentle when he wants to be and finds satisfaction in all the little things he can do to make Ash happy, be it making them packed lunches for tomorrow or finding someone to look after the kids (when they were younger) so they could have a night in, just the two of them. Ash can certainly be romantic as well, but he tends to make larger gestures, setting up dates, buying flowers, that sort of thing. 
Who wakes up first: Paul tends to be a more early riser. Even after all these years Ash still sleeps in and through all his alarms. He needs the most powerful alarm of all ‘husband telling him he’ll be late for work’ to ensure he wakes up in an instant.
Who comforts who the most: Ash is more open with his emotions and expressing his frustration or sadness, so Paul tends to more frequently offer support when Ash needs it. At the same time, while Paul is more withdrawn in how he expresses himself, Ash is really good at reading him so he knows when his husband needs support and comforting and Paul doesn’t mind showing his more vulnerable side if Ash is the one comforting him.
The cuddler: Ash is pretty cuddly, but the real answer here is Pikachu, who loves to fall asleep on Paul’s lap and even sometimes steals Ash’s spot cuddling Paul in bed. 
The big spoon: Paul usually, since he’s the taller one. Ash sometimes likes to be the big spoon if Paul is in a rough patch though.