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Yes, it does seem a bit weird to "spray" your Pokémon with a Potion to recover their HP. Assuming that HP is the Pokémon's stamina, it seems a little more logical for a pokemon to drink something like Fresh Water to recover its health instead of being sprayed by a magical, HP recovering canister.
Turtwig, mainly because I've usually picked a fire-type on previous game and wanted to try something different this time around... and Chimchar just didn't appeal to me.