Question

Can Fire Pokemon get burned as of gen 5 because of Scald?

Answer 1

No, they cannot. Fire-type Pokemon are immune to burns, regardless of how the burn would have been given had their immunity not been there.

More info

Comments

are poison types immune to poison too?

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Yes, they are.
Source: http://bulbapedia.bulbagarden.net/wiki/Poison_%28type%29 , you can find it using ctrl + f with parameter "toxic" (without ")