I'd probably say either Lapras or Slowbro is a better choice for the water member. Surf is kind of wasted on a clearly physical attacker like Gyarados and I'm not sure if Johto has many Waterfall areas that would make Gyarados' uses essential outside of battle. Ice Beam is also a far better ice type move than Ice Fang.
I'd probably say Tyranitar isn't worth it, considering the only place you can catch Larvitar prior to the post-game is the Safari Zone at Level 17, which will be pretty underlevelled for that part of the game.
Going to catch Growlithe soon and probably evolve it once it gets Flamethrower. Will use it as a Special Attacker with that and Dragon Pulse instead of grinding it to lv 48 for Flare Blitz.
1. I've looked into many resources revolving around the game.
2. It's pretty easy to see how team composition would work when considering the game's main trainers and the difference in physical/special stats.
3. Refer to 1 and 2
Have you noticed how stupid RNG is in this game? I recently played through and I swear I always got flinched, paralyzed, statused, hit in confusion, etc. way too much. Seems so much worse in this game (and SS) than any other.
The one I notice most is that high accuracy attacks miss extremely frequently. Getting hit in confusion is also quite noticeable. I have Confuse Ray on Gengar currently and my opponents never seem to hit themselves.
For a fire stone, the only place you can look right now for one is to beat the school kid on Route 36 (not sure if from the first battle or the rematches). All the other methods of getting one are part of the post-game.
As for the Dragon Scale, do you have access to Mt. Mortar yet? That's the only place in the main story you can get it, unless you'd rather try and catch loads of Horsea and Seadra in the hopes they're one of the 5% holding one .
How far are you now? Waterfall's available in the Ice Path and can be used once you've got 8 gym badges, so it sounds like you shouldn't be too far off from acquiring it based on how your team is right now.