I just wanted to know as mine is low key, just really wondering.
Toxel evolves into Toxtricity Amped Form if its Nature is Hardy, Brave, Adamant, Naughty, Docile, Impish, Lax, Hasty, Jolly, Naive, Rash, Sassy, or Quirky. Toxel evolves into Toxtricity Low Key Form if its Nature is Lonely, Bold, Relaxed, Timid, Serious, Modest, Mild, Quiet, Bashful, Calm, Gentle, or Careful.
source You can change the stats by using mints, in case you want an amped Toxtricity with modest stats or something like that. Amped form's second ability is plus, and it learns venoshock and shift gear by level up. Low-key form's second ability is minus, and it learns venom drench and magnetic flux by level up. I don't think there are any other differences. source