I actually think the answer is
Pokémon, or a game of pokémon
My name sets afire confusion and ire.
Least sure about this clue, could be because of the accented 'é' in pokémon, which has led to confusion about the pronunciation
With creatures acquired, battles change on the fly.
Obviously as the game progresses, you catch (acquire) more pokémon and each battle changes accordingly based on the 6 you carry
Bring with you your child, for it's once in awhile.
Again, not sure about this one, possibly referring to Pikachu, Ash's "child" in the original series
When monsters say "hi," I request a "goodbye."
In most games, when you encounter a random pokémon in the wild, you run from it to save time
When you see me it's often when I'm not on the bottom.
Speculation: In classic pokémon battles in the game, the wild pokémon is on the top side of the screen and the trainer and his pokémon are on the bottom side
If you know that I'm there, you know how to prepare.
In the games, if you know you'll be facing wild pokémon a lot, you'll bring "Repel" (or Super, or Max) thus being 'prepared'
Its a long shot :)