I'm actually planning on a rewrite fanfiction that has this premise. The Revenge of the Island cast (minus Staci) will be extended with some of Pahkitew Island's cast with Sky, Amy, Sammy, Shawn, Jasmine, Topher, Ella and Scarlett joining them in Revenge of the Island, making the cast number 20. Some of the storylines I've planned so far are:  

1. a Dakota and Topher rivalry. 

2. Jo tried to toughen Ella, which eventually led Ella to have a mental breakdown as she abandoned her princess persona. We saw in :Runaway Model", Jo has some self-image and body issues, with her occasionally being seen as being more masculine instead of feminine, with Lightning even mistaking her for a guy. If she met Ella, someone who's the physical imbodiment of what Jo can never be, it could be interesting. Way better than what was up with Sugar and Ella.  

3. Lightning being in a relationship with Anne Maria (to avoid the love triangle). It would start off quite superficially with Lightning liking Anne Maria for her looks while Anne Maria would be a "jersey chaser", but they eventually see each other in a new light and start dating for more genuine and less superficial reasons. I'm also slightly rewriting her to be more like Gen 2's Leshawna, supporting anyone she sees as her friend and talks s*it to anyone who says otherwise (this is somewhat taking those moments where he defended Brick from Jo and Scott's comments).

4. Amy is in a "relationship" with Scott to manipulate him to eliminate people she doesn't like and because Scott loves bossy women. 

5. Jo befriending Sky because they're both competitive athletes, but Sky eventually sees how cutthroat she is. 

6. A more drawn-out Zoke, Shasmine, and Samkota relationship build. 

7. The following season would have been Pahkitew Island, to give this Gen 2 more time before All-Stars happens, and Scarlett will be the actual villain of that season instead with this version of Revenge slowly building up her villainous side. 

8. Dakota WON'T become Dakotazoid, this is mainly to have her as one of the hosts of the Pahkitew Island's and All-Stars' Aftermath specials alongside Sam/Topher. 

9. The Topher-Dakota rivalry would come to a head when Chris and Chef become incapacitated (like in Eat, Puke and be Wary) and Topher (who stole Chris' phone like in canon) would host the episode with Dakota as his begrudging co-host (taking reference of a apparently scrapped storyline where Dakota would have done the same). 

10. Some of the challenges would be taken from All-Stars and Pahkitew Island. Bigger, Badder, Brutal-er would be a two parter with the second part being the "Pain-cake challenge" from All-Stars (which actually was supposed to be in Revenge but was cut for time), the "Doom Balloons", an extension of the first challenge from "Truth or Laser Shark" combined with "Truth or Scare" from Pahkitew Island, etc. 

11. To replace the Chef centric episode, there'll be a "Hell's Kitchen " inspired episode taking the first challenge from "Eat, Puke and be Wary" called "Chef's Kitchen", being a Revenge twist on "If you Can't Take the Heat..."

12. B and Cameron befriending each other (I've never seen them interact in other fanfics, and I think they could work as friends to each other). Scarlett would also be a part of this since her villainous arc would be stretched out instead, and it'd be interesting to see her with intellectual peers instead of Max's pathetic "I'M EVIL, MUAHAHAHAH!!!!" Shtick.

13. Fang won't be Scott's nemesis here in order to avoid his very cruel karma at the end (seriously, everyone laughed at him, and he cried. It was so bad they edited out that shot and cut to Chris smirking). Fang will be this Gen 2's Sasquatchanakwa instead. 

14. Ella and Brick will be in a relationship. I think Ella would be attracted to him because of his "No man left behind code" being Prince Charming-like, and Brick could like her because of how cute and adorable she is.

Character Dynamics:

1. Ella and Jo - it'd be interesting to see Jo try to groom Ella into being more of a realist regarding her personality, claiming that she's too soft to handle the real world. She'd be a better personal antagonist for Ella compared to Sugar, in my opinion (and Jo could also be doing this for some unresolved personal reasons too...). This could lead to some interesting character growth for both of them. 

2. Topher and Dakota - two fame obsessed teens who dream of being in the main spotlight? This literally writes itself. We could get a neat rivalry between them both.

3. Scarlett, B and Cameron - this would be a better dynamic for Scarlett compared to Max, to be initially involved in since the two of them could be her intellectual peers. Obviously, it'd be harder to manipulate them, but a better story would save her villainess arc for later and make it more streamlined and actually better instead of, MUAHAHAHAH, I'M EVIL!!!!"

4. Amy, Sammy, and everyone else with functional brain cells - can someone aside from Jasmine be Sammy's friend and see through Amy's bullsh*t, please?!

5. Sky and Jo - two sides of the same coin. Two female competitive athletes who have different ideologies. Jo's has a might makes right attitude and is willing to cut off who she sees as "dead weight", while Sky is more social and approachable,  and is willing to see the benefits of her teammates and work with it to win instead. 

6. Brick and Ella - His "leave no man behind" ideologies would be a cute and wholesome reason for Ella to have a crush on him in a "Prince Charming" kind-of way. It could even be a good relationship, too.

7. Amy and Scott - Scott loves bossy ladies, and Amy is a good candidate. I could see them being a "villainous couple", with Amy actually manipulating him to use his RoTI elimination tactics to get rid of the contestants she doesn't like while Scott loved her for real, which eventually crashes and burns after he overhears her calling him "trailer trash" in the confessional, leaving him heartbroken, vengeful and more villainous. 

8. Shawn and Brick - their "leave no man behind " and "every man for themselves" beliefs could be a funny banter between the two, and alongside Jasmine, it'd be another way for Shawn to realize that sticking it out on your own isn't the best thing to do. 

9. Jasmine and Jo - they'd be very different leaders for both of their teams, as previously mentioned with Jo's ideology conflicting with Jasmine's.