I play with the volume down low so I don't have to hear their tantrums. 
On a more serious note, the 'family' aspirations give a bonus trait that allows you to form fast relationships with family members. Also there are some interesting lot traits and club perks that may assist, oh and don't forget the parenting skill.
I've also found that having parents becoming good friends with the toddler/s helps somewhat. I've been able to have both parents become good friends with two nooboos within about 3 1/2 sim hours. I have 1 parent at each bassinet and then do 6 'cuddle' interactions. and then another 6 of the same. That seems to get them to good friends with that parent within that space of time, and then I swap parents over. It is possible there are quicker ways of getting it. Feeding them and/or changing dirty diapers seems to make the process of good friends quicker. I stop as soon as I get the message that parent sim is good friends with nooboo sim, I don't know if continuing on with socials to improve the good friend status provides bonuses to future interactions with said nooboo when they are a toddler and so forth.
I've also found that if you give them a 'Wabbit' tablet thingie they can pick up most of the toddler skills quite alright (just not potty) and that the toddler slide is quite good for them picking up movement skill quickly. Finally, I give them the chance to do some 'free range wandering' going from object to object saying "what's that" about just about everything. Even with no one around to tell them what it is, thinking skill (and perhaps speaking skill) seems to improve, plus the walking continues their movement skill. Having toddlers hug others (including other toddlers) is awfully cute 
With eating ... I've done away with high chairs altogether now. A parent makes the food - generally garden salads. When the toddler/s are up and about, I drag servings of the food out of the fridge and onto a surface. I direct the toddler to go and eat said food and then once they return the plate to the table, I either put it back into the fridge, or into that bin that gives you money for using it. The toddlers are happy to eat either on the ground or on their toddler beds.
I randomly rolled twins as both having clingy once ... that was painful. Both wanted the same parent most of the time. I had one roll up silly and that wasn't too bad.
The biggest issue I seem to have with toddler skilling is potty. Their third level seems to take forever when left to their own devices. So I have a parent help them, which seems to be a quicker process, even for independent toddlers.
Seems like all the above needs some extra research, FOR SCIENCE!!!
Thanks, Deklitch! My "main" Sim in this case, is my founder for my alternative dynasty try, where I'm running the "same" Sim but as if she has an alter ego somewhere in space/time. The Prime Founder has no problem at all with her toddler who was given the Charming trait. So easy! (I still didn't get all her skills to level 5 and am wondering if it's possible on normal life span.) That one loves her Mom and Dad, (Don Lothario in that case), learns quickly and is so easy. This one is almost always angry or sad.
"Potty" for number one was a breeze. I always had a parent or in house adult ask till she reached 3 and she would autonomously ask for help. Number two prefers to use her diaper even when asked and no matter how close she is in her need. She will give an evil look, refuse, and then either try to run off or just stand there and pee. I've almost given up on her trying to be nice to Mom, who does persevere with her. I guess things really are different in alternate life spans!
I like that advice about free range wandering! I set several stuffed animals up in my first reality and she just went from one to the other and learning to talk was actually maxed quickly. This one wanders to the point I had to block the stairs! She grabbed a dish of breakfast scramble and I sat back and watched her climb down the stairs, (instead of sitting on anything to eat even though she was in the red with need), from the second floor to the basement! In the basement she ate just enough to go from red to yellow and then wandered into another room to pitch the dish onto a keyboard! When Mom found her she was repeatedly defiant and so proud of her bad behavior it was actually funny. I don't like to use high chairs either but this one prefers them and will throw her food onto any available surface if she isn't in one to eat. The look on her face when she threw the food onto the keyboard was priceless. I can imagine her say, "So there! So much for your stinky food, Mom! Now YOU clean it up!"
You are not alone, Joria.
If you ask me, toddlers aren't really scripted that well. Their standard response to any low need is anger and wanting sweets. I find that unrealistic, along with many other things. And what's with the getting angry or sad about having played with the same thing for a while? I would think a real toddler would simply abandon the activity and find another. Potty accidents upset real toddlers for hours?
I know you probably can't, but personally, I age up the really difficult ones. I wish to have fun when playing, not pull at my hair in frustration. No game has ever driven me to the edge and beyond as The Sims 4 has.
You are so right! If my own kids were this obnoxious I probably would have had only one instead of six! The first time I played with toddlers was in the Tech Challenge and I thought life with toddlers would be a snap after that. The poor kiddies were always filthy and had very little to play with in No Tech, but they, and I breezed through that stage. I tried that challenge several times, (lots of fails!), once with twins, (nightmare!) and finally with an independent toddler who just learned it all with little effort. This one shows just how badly that trait can become. I think if I was just playing this one for fun, (my normal mode of play), I'd cheat my way around or do a "do over". But since it's a dynasty I'm stuck.
@Joria If you think one toddler is bad, try having three ... at once ... triplets ... 
But seriously, don't use high chairs and watch what they eat as some foods, such as Animal Crackers for example, will give them a sugar high and then they crash and become all cranky, lol. I don't seem to have much of an issue with toddler tantrums I don't know why that is, I have my parents interact with the toddlers a lot and they take a real hands on approach with them, so maybe that helps. One thing that I've found that keeps them in a good mood is to have a Laser Light Show in the same room with them and using the parenting skill can really help with their needs too.
Toddlers are super cute and I have a lot of fun playing with them, there are just so many cute interactions you can do with them, it's less stressful when you're aren't trying to raise three of them on a time crunch though. 
I can't even begin to imagine triplets!!! Bless you for your courage!
I really like the Laser Light idea! My overly pampered toddler, (she literally has it all), might benefit from that. So far her favorite thing to do is talk to herself in the mirror or play in the ball pit. I have to admit, even with her obvious dislike of her Mom she really is adorable and cute. When she's doing something charming she's a joy to watch, but put Mom on the scene and it all goes horribly wrong. Mom just can't catch a break with this one. I really am beginning to think the nooboo years are very, very important. In this case Mom was trying to max her skills and gain promotions and too often would let the nooboo cry alone. Dad would show up, (better relationship with Dad), or the live in gardener would more often show up for all her needs. Mom would change diapers and feed but seldom did all the nooboo stuff as she was usually too tired herself. In reality number one, that Mom was always ready to drop her things to tend to the baby. I guess it's more like real life than one imagines. Can't always make up for those missed opportunities.
