Lizardmen in 8th edition: Core

Lizardmen have some really good options in their core selections. Unlike some other armies, you're not likely to ever have a problem not reaching your 25% core requirement.

Saurus Warriors:
I love these guys. They took a decently sized hit in fighting power with the shift to 8th though. Their low initiative almost guarantees they go last every time which means you need to field them in blocks big enough to ensure a full two ranks is still alive (to get all your attacks back) or three ranks if you give them spears. Spears also only give supporting attacks in 8th so a block of warriors that got 20 attacks with spears in 7th will still only get 20 attacks with spears in 8th. Their are ways to mitigate their weaknesses however (Lore of Light) and with the right support, and a decent block size, I think these guys are solid.

Skinks:
I personally prefer these guys as skirmishers. There are however some potential uses for these guys in 8th edition. They are cheap enough that you could field them in giant steadfast blocks. If you take them in big blocks, you can add some kroxigors to the unit to give it some killing potential. This gives you a great way to protect your kroxigors from ranged and close combat threats. Pair big steadfast/hordes blocks of these guys up with some hard hitting units on the flank and I think you might be able to field a competitive army around these guys. They can also be fielded as cheaper throw away blocks than the skirmishers. Since they don't have blowpipes as an option, the extra range on the javelins has actually helped them so they might be good cheap harassment/redirection units as well.

Skink Skirmishers:
These guys lost some things but gained others. Of particular importance is the ability to march and shoot which is absolutely fantastic. You will still be single shotting with your blowpipes most of the time because you want 6s for their poison but that doesn't matter. Take them in units of 10-12 and they make fantastic redirecters, harassment units, and can even do some damage to non-infantry units. Don't bother with the javelin upgrade. The range on them increased to 12" but they now take a penalty for long range. Blowpipes and the chance to double shot sometimes is much more useful than getting non-poisoned hits on 5s.

Jungle Swarms:
I don't know what these guys are for. I didn't know in 7th edition and I don't know now. Really, the only thing I can think of is to annoy your opponent a little. Set it up so he can waste a full unit charging them or get charged in the flank by them and held up for a while. These things aren't going to survive at all being attacked by anything on the front but if you can limit the attacks back of a unit by hitting the flank or rear, it should last a turn or two. They're really expensive though so I'm thinking they still aren't going to be worth it. I'm thinking you'd want to field these in 2-3 bases. 2 is cheap enough to be a throw away unit but any shooting or magic will quickly knock it down to 1 and make it worthless. 3 will weather a little firepower and give you enough oomph to last a round or two of combat.