Honestly, looking at the team you posted vs what you could’ve used tells me you’re not understanding how to create a team.
The bombwelter is better than everything other than toothless. It’s ability to pump everything else up will actually be useful vs the molten who takes forever.
Both your 3* reds are faster and just as powerful as the molten (at only 3* himself) plus the knock rocket ability is long term and can help endure.
2 of your dragons do damage over turns, which means your opponent dragons have extra turns to attack you.
You have no synergy, no speed, and no lasting endurance.
Also your fang hook is “very fast.” Take advantage of that.
Start piggybacking abilities and create some synergy.
Lastly, and a lot of new people struggle with this: tile damage is key. Setting up combos for down the road. Knowing which ones are best to move to maximize damage and cascades. Having cascades every turn of 2, 2, 2, 2, isn’t as good as 1, 1, 3, 3. This is chess, not checkers, you have to plan 5 moves down the road. Planning and settling for crap moves so you can get special gems 3 turns later with a great cascade is key.