From StrategyWiki, the free strategy guide and walkthrough wiki

After completing the Lapis Cave dungeon, you will arrive at a save point where you can access your inventory. When you have finished, you have the choice of taking the Rocky Path or proceeding straight to Mt. Blaze. Rocky Path brings you back to where you started.

[edit] Items

This is the least amount of items you'll need for Mt. Blaze:
Reviver Seedx3
Max Elixirx3
Oran Berryx3
Apple/Big Applex3
Heal Seedx3(optional)

[edit] Enemies

Rocky Path is an optional section of this dungeon for strengthening a weak rescue team in preparation for the upcoming battle with Moltres. None of the Pokémon here will join your team.

Rocky Path

Name	Type	Level	EXP	Levels seen	Recruit Rate
Pidgeot	L / G	36		1-4	N/A
Nidorina	M	16		1-4	N/A
Nidorino	M	16		1-4	N/A
Zubat	G / M	17		1-4	N/A
Numel	F / J	14		1-4	N/A

Mt. Blaze is a 12 floor dungeon containing Slugma, Torkoal, Rapidash and Magby.

Mt. Blaze

Name	Type	Level	EXP	Levels seen	Recruit Rate
Pidgeot	L / G	36		1-3	N/A
Magby	F	17		1-5	9.5%
Numel	F / J	14		1-6	8.1%
Slugma	F	16		1-12	11.4%
Shuckle	A / O	15		5-9	6.9%
Torkoal	F	15		7-12	8.1%
Rapidash	F	40		8-12	N/A

After the twelfth floor, you come to another save point, from which you continue to Mt. Blaze Peak, with 3 floors containing Fearow and Arcanine.

Mt. Blaze Peak

Name	Type	Level	EXP	Levels seen	Recruit Rate
Fearow	L / G	20		1-2	N/A
Arcanine	F	20		1-2	N/A
Moltres	F / G	52		3	30%

[edit] Boss battle: Moltres

On the third floor, you encounter Moltres for the first time. After defeating him, he will allow you to pass. Water-type is best agenst him. Level 20 and up is a good Level to be in while being in the 3 boss battles.