I am setting up a one shot for my players. The adventure is set up for 5th level players and there are kobolds who are NPC's. I want to use the Kobolds as PC's. I have character sheets for the Kobolds but I don't know how to tell if they are leveled appropriately to defeat the dragon at the end, and if not, how to level them up accordingly.

these are the basic stats of the dragon

Young blue dragon, large dragon; neutral evil

Armor Class 18 (Natural Armor)

Hit Points 152 (16d10 64)

Speed 40 ft., burrow 20 ft., fly 80 ft.

Str Dex Con Int Wis Cha

21 ( 5) 10 ( 0) 19 ( 4) 14 ( 2) 13 ( 1) 17 ( 3)

Saving Throws DEX 4, CON 8, WIS 5, CHA 7

Skills Perception 9, Stealth 4

Damage Immunities Lightning

Senses Blindsight 30 ft., Darkvision 120 ft., Passive Perception 19

Languages Common, Draconic

Challenge 9 (5,000 XP)

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And these are roughly the stats of the Kobolds. There are going to be four of them and each one will have a Dire Weasel with a CR 1/2

Small humanoid (kobold), lawful good

Armor Class 14 (studded leather, shield)

Hit Points 58 (9d6 27)

Speed 30 ft.

Str Dex Con Int Wis Cha

14 ( 2) 13 ( 1) 17 ( 3) 8 (-1) 10 ( 0) 8 (-1)

Skills Athletics 5, Perception 2

Senses Darkvision 60 ft., Passive Perception 12

Damage Immunities Lightning (see Shield)

Languages Common, Draconic

Challenge 2 (450 XP)