Some crackships which came to mind

Shipping. Some fans love it, others hate it. I believe that any ship is valid long as it has a well-developed story or is so ridiculous that has its charm. These are some couples who would like to read or write in a fanfic.
Coco Pommel X Babs Seed: I will start with the most controversial. First let me clarify that I'm talking about a older Babs Seed; at least 16 years, so putting some drama. Also I do not think they have many years apart, about 6 or 7 years; I consider Coco younger than Rarity. The funny thing is that Coco can wait for her to have the age of consent, Babs not so much

Moon Dancer X Gilda: They do not have much in common, except for a complicated relationship with his "best friend", however are one of my favorite secondary characters and I like that Gilda is with someone smarter and nerdy.
Moon Dancer X Flash Sentry: I have nothing against the pony Flash Sentry but the thing I'm most a Twixie fan. It occurs to me that Twilight can present Flash to Moon Dancer, acting as matchmaker.
Lighting Dust X Zecora: In this pair I have a more developed idea. Lightning Dust is making a Sonic Rainbow but ends up falling on the Everfree Forest, nearly breaking all their bones. Zecora finds her and cure, but for the severity of his injuries can not take her to Ponyville, so Lighting has to stay his home until she recovered. As more time they spend together, more they begin to feel attracted to each other.

Maud Pie X Garble: Ok, I did not invent. The honor has PurfectPrincessGirl who made the picture you see above.
Limestone Pie X Fido The Diamond Dog: This ship is not my idea entirely. The deviant Art artist StarryOak already made a OC hybrid called Granite, daughter of Marble Pie and Rover, but I think Blinkie would be more lover of dogs... . Anyway, I think a rock pony would be a match for a diamond dog and Limestone would be a perfect tsundere.
Splitfire X Firefly (Rainbow Dash's mom): My idea is that the Rainbow's parents divorced when she was very young. This shipping already worthwhile by the reaction of Dash: "¡¡Oh, my gosh!!. Are you dating my mom?." or "¡¡Oh, my gosh!!. Are you dating my mom?"
Daring Doo X Bifrost (Rainbow Dash's dad): Same as above. Although I imagine they were like an adventurous couple.
Pinkamena Pie X Rainbow Blitz: I thought that might be clones made by a mad scientist (and added the chromosome Y in Rainbow's ADN... for science!).
Granny Smith X Grampa Gruff: I thought this just to annoy Applejack and Gilda, but I've been that this couple have a funny dynamic. Maybe they used to be a couple when they were young.
Princess Luna X Scorpan: We do not know much of FiM Scorpan, but from what I saw from its original version, it would be a good match for Luna.
Adagio Dazzle X Star Swirl The Not Yet Bearded: Now, in this really take crack when I thought it . Anyway, my idea is that Star Swirl reincarnated in a young boy (something like Clow Reed).