This guide will allow you to get the platinum trophy for The Sims 4 in a much quicker, easier, and less tedious way. To begin, you will need to login to an EA account to access the gallery. If you do not already have one, you will need to create one which the game will guide you through. (Thanks to de_digibeet for pointing this out)

You will need the following downloaded from the Gallery and they can be found by searching for the EA User ID in Brackets:

• Trop-hee Family (Malachen)
• Trop-hee Family 2 (Malachen)
• Legacy Trop-hee Family (Malachen)
• Ghost Family (Naomie_Len)
• Basketcase Trophy + (Naomie_Len)
• Grim Reaper Family Trophy (Naomie_Len)
• Circle of Life 2 (NZJoey89)
• Search the gallery for triplets and download one of the many Sims that are pregnant with triplets.
• Search the gallery for Black Widow and download one of the families that has similar looking Sims to Trop-hee Family 1 and 2.

Once these families have been downloaded, we can begin getting the trophies out of the way. A number of people have reported issues downloading some of these families. A few workarounds are in place so if you cannot find them via Account ID then try searching Item Name and searching for Basketcase Trophy +. This should find Naomie_Len and you can access her profile and other families from there.

The video guides below shows how to get the platinum trophy using the details contained in this guide. If at any point you are unsure on the text guide, refer to these to get you through.

BushidoCypher guide with Commentary

 

Platinum Speedrun - Part 1

 

Platinum Speedrun - Part 2

Start a new game and load from the Gallery the family you downloaded for the  Black Widow trophy. As soon as the lot loads, you will receive the  Full House trophy and you should see 4 people keel over and die. Wait for the Grim Reaper to take them all and then open the menu and click Manage Worlds. Once this has loaded, select the family that you are playing as and click the 3 dots then click Manage Household. In this screen, you should have a pencil icon to change the family. This will put you back into Create-a-Sim. Enter the Gallery again and merge the Circle of Life family in and make her the wife of one of the survivors. Load the household again and make sure that you have set Sim Lifespan to Short in Gameplay Options then just wait for her to die.  The Circle of Life will pop alongside  Black Widow 3/51 popped.

Start a New Game, Load the family from the Gallery and place them in any lot. Wait 10 seconds and  Hello, Darkness, My Old Chum will pop. 4/51 popped.

Start a New Game, load the Ghost Family and place them in a lot. Wait 10 seconds and  Ghost Family will pop. 5/51 done and again this shouldn't take any longer than a minute depending on loading times.

Start a New Game, Load whichever Triplets Sim you downloaded and fast forward till they are ready to give birth. Click the Sim and send her to the hospital to give birth. Once they have given birth, you will receive  Triple Play. Once this is done, bake a cake with the Adult female Sim and put candles on it. Blow them out with her to get  Old & Wiser. 7/51 popped. This will take around 10 minutes depending on how long the Sim has to go to give birth.

This one is easy. Start a New Game, select Legacy Trop-hee Family from the Gallery and place them in any lot they can afford. Wait 10 seconds and  Legacy Player will pop quickly followed by  Alphabet Legacy. 9/51 done. This will take no longer than a minute depending on loading times.

Start a New Game and open the Gallery in the top right corner. Select "Trop-hee Family" and click Place Household. It will then ask if you wish to Merge or Replace the family. Click Replace and your Sims will appear. Once this is done, simply choose a lot to place them down. I suggest using "Streamlet Single".Once the Lot has loaded, the  Rosebud trophy will pop within about 10 seconds, the Journey to the Platinum continues. Send Entertainer Tate to "Practice Speech" in the mirror in the Bathroom and enter Build Mode. Buy 2 of the most expensive computer and put them at either end of the table in the living room. Also, buy a microphone and place it down somewhere that is accessible.Re-enter Live Mode and select Writer Spencer-Kim. Enter the Rewards Store from the Aspiration menu and buy the following potions:

• Insta-Lean
• Insta-Large
• Inspired

Once you have bought these, they will appear in her inventory. Drink the Insta-Large potion and wait for the character to finish. You can tell when she has because she will get a lot fatter. Now drink the Insta-Lean potion and she will shrink and you will get the  My, You've Changed! trophy. Now drink the inspired potion and get her to write a genre book from the computer. Any genre will do but Mystery seems to have slightly more success writing a Bestseller which is what we need to pop  Over-Achiever. If you don't get it after writing the book, buy another Inspired Potion and try again.While you have been doing this, Entertainer Tate should have got level 10 in Charisma and popped the following trophies:

•  All Nighter
•  Beyond Repairs
•  Bow-dacious
•  Cast Away
•  Code Monk
•  Connoisseurus Rex
•  Elementary
•  Fired Up
•  Games Within Games
•  Green Thumb
•  Introvert
•  It's Not Brain Surgery
•  Ivory Tower
•  Literal Genius
•  Mael-strum
•  Mischief Mastered
•  Refined Palette
•  Smooth Talker
•  Straight for the Jocular
•  Tender Loving
• The Most Interesting Sim in the World
•  Tungsten Chef

If she hasn't quite reached it, fast forward till she does. Now you should see a few plants outside the lot. Use Entertainer to harvest any you can see and take cuttings as well. Once that is done, plant any flowers or seeds you have and select "Tend Garden" with Entertainer and do this each day till they are fully grown.While you are waiting for them to grow, make sure Daily Tasks for each Sim are done so that when they next go to work you can select "Work Hard" and they should get promoted to the next level, thus unlocking the trophies for the respective careers which will be the following:

•  Are You Entertained?
•  I, Spy
•  Startup Upstart
•  The Pen is Mightier
• World Competitor

While waiting for each of these trophies to pop, keep checking on the plants and when they are fully grown, click on one and click "Graft". Graft the cutting to it and you will receive  Splice of Life. As each Sim gets their career trophy, remove them from the family to speed things up but don't remove Entertainer.

Go to options and change Autonomy to Off under Gameplay options. Enter Build Mode and buy the GeniusVision TV and The Landlord Whisperer Radio. Also buy a few rubbish TVs and put them around. Use Entertainer to Salvage for Scrap on the rubbish TVs and then upgrade the TV and Radio with Super Reception. Now select to watch each channel on the TV and just queue them up. Then pick a radio station, click to listen to it, then wait 2 seconds and change to the next station. Then click to listen to it, wait 2 seconds, and then choose the next and so forth until you receive  Channel Surfer.

When you only have one Career trophy left to pop (Likely to be Writer), head to the next step.

Enter Manage Worlds and select the Trop-Hee Family household to manage and then edit the family like with the Black Widow family. This time, delete the 4 people who are at the top of their careers, then add in Trop-hee Family 2. This time buy the cheapest rocket for 5k Simoleons and place it outside. You should be able to fit it just outside. Build the Rocket with Astronaut Payne. Start building a relationship between Astronaut and Business. Once they are in a romantic relationship, you can get them to WooHoo in the built rocket for the trophy  50-Mile-High-Club.

They will easily be able to get to 100/100 if you keep talking about Games and Game related things. Once one of them has reached level 10 in their career and reached max friendship, press , , ,  all together to load the a bar at the top. Press  and type in traits.equip_trait ghost_laugh while the Sim that has reached level 10 is selected.

This will turn them in to a ghost. Select the ghost and use their phone to split with household and give them enough Simoleons to move into the Bargain Bend next door. Once they have moved in, select Manage Worlds from the main menu and go back to playing the original household. If you zoom out, you should be able to see the ghost next door, if not, visit their household and you will see them there. Simply select them with the spouse Sim and goto "Friendly..." keep clicking "More Choices..." until you see "Invite to Household". This will move them back in and pop  Ghostly. Then select to WooHoo with the ghost and this will pop  What Would It Be Like?. This must be done in the bed and not the rocket. (Thanks ​ObsiEez​​​ for reminding me of this)
Do each person's daily task and send them to work. Make them "Work Hard" while at work and they should get their promotion next time they go to work and pop the following trophies:

•  Captain of Industry
•  Flying Colors
•  Stellar Work
•  Suave Criminal
•  Up a Notch

As each person gets their trophy, remove them from the family and get any people not at work to nap to speed this step up.

We are now done with this family are up to 49/51 trophies. This shouldn't take longer than 45 minutes but the game can lag a bit sometimes. Remove any family members that have received their Career trophy to make this run a bit better.

Start a New Game, load the Basketcase Trophy + family from the Gallery and place them in any lot. Wait 10 seconds and the  Basketcase and the  Ultimate Sim Guru trophies will pop. 51/51 done.

Congratulations on your platinum trophy!

Special thanks and credit go to Naomie_Len, NZBigC, and Phantochi for the extra uploaded families and tips for some of the more manual trophies.

Thanks to the numerous people in the comments who have pointed out a few errors in the guide.

Enjoy your brand new shiny platinum trophy!