I put Sabertooth because the first movie kinda butchered their whole connection. I mean I understand how they can meet in a different place and setting as the X-Movies universe is different than the comics, but just the fact that Sabertooth is to Wolverine what Venom is to Spiderman. Both are stronger, faster versions of the origional (tho sabes came from DD comics), and they mess with the hero on more of a psychological way, then ultimately get beat thru sure persistence and will than brute force.
I wouldn't mind Deadpool but my problem is that he would fit better as a small cameo then lead into a spin off, and maybe a funny side-kick at best. Deadpool is funny but occasionally dark, Wolverine is most likely going to be a serious dark style. Deadpool my be played a bit more serious, or be too much a villain in normal fans eyes to the point they wouldn't want to see a spin off of him (despite how much comic fans like him, not sure how far Deadpool's fanbase could carry his movie). I'd also like to see Omega Red.
One thing that might work tho is Kitty Pryde being upset over Iceman and Rogue hooking back up in the last movie, and her stowing away in Logan's truck and getting mixed up in it. Jubilee was in the first two but two different actresses, and obviously not enough to get a line in so they prob don't care. Wolverine has trained Kitty tho, and would make sense to bring her in as a side kick. Ya tho, Sabertooth as the intro villain, Omega Red as the main, and maybe another Deathstryke (since the movies are differnt, and as a lead in) who can be made in a similar way to Omega from one of Wolverine's old girlfriends in some way linking to Weapon X. Also would like to see Maveric, maybe like a war buddy type who was experimented like Logan (like in the comics), but have him instantly recognizing Logan but Logan not recognizing him til near the end maybe when they kill Marveric or something motivating Wolverine to fight more. Poorly put together, but u get the just of what I mean I hope.