My other army is Ogres, and they can be tough if the opponent is on his game. They aren't as strong in smaller games in my experience though, so you should have an advantage (especially with the Slann)
For a 1500 point game, you will need 375 of your points to be from the Core choices. I think the battalion box comes with 20 saurus and 12 skinks, so you might have to use some of the temple guard models as more saurus. If you want the temple guard to go with your Slann, however, you could use two of the Cold One riders as "fillers" in their unit and bring them up to 24.
Here is the list I would try against the ogres using the models you have. It uses most of your models, and gives you a good variety. Remember, this is just a suggestion, and half the fun is figuring out your own answer.
Slann: General, Standard Bearer. Plaque of Tepok, Divine Plaque of Protection, Focused Rumination
Scar Veteran on Cold One: light armor, Piranha Blade, Charmed Shield, Luckstone
30 Saurus, full command (using the Temple Guard models here)
12 skink skirmishers
Stegadon
7 Cold One Riders
Salamander
The Slann will be by himself, so keep him behind the lines to avoid being charged (but still in range to use his leadership and banner) Lore of Life is always a good choice for spells, but Light or Shadows is good, too. Ogres fear the Pit of Shades as much as Lizardmen! In friendly games with pals, I don't usually take Life, as it can be overwhelming.
The Scar Veteran goes with the Cold One Riders, and his weapon will be great against the multi- wound Ogres. He can do well against enemy characters, if it comes to that. The Ironguts can cut down your cavalry if you hit them head on, so be sure to go for a flank. Also, don't let him cast Bonecruncher at this unit; it ignores armor and can do surprising damage with a good roll. (My Ogres love to get Chaos Knights with this spell). Cold Ones move fast and hit hard, so be sure to get the charge and go for a weak point.
The stegadon's giant bow will be good until you get close enough to charge; don't forget it does D3 wounds just like a bolt thrower. Combo- charge it with the Cold Ones, or try to get something in the flank when you get close enough.
Your saurus will have plenty of ranks to be steadfast when they get into combat for at least a while, so just make sure the cavalry or stegadon is waiting to support them with a flank attack. I'd deploy them 5 wide, 6 at the most. Protect your own flanks or all is lost!
Salamanders are one of our best units, but Ogres are one of the few armies they don't do as well against- they're too big to get many hits. You can still get good kills, though. Flame the Gnoblars if you can to get them out of the way. He can have a banner for his BSB or Ironguts that allows him to transfer the spell you cast onto another of his units, so with the gnoblars gone it narrows his options.
Make sure to get rid of his Gut Magic spells whenever you can. They can stack up and make his units a nightmare to fight. Even if you have to use your own power dice to do it, dispel the magic on any unit you're in combat with.
Well, those are my thoughts. Try whatever you like, have fun, and let us know how it goes!
