I think there is a misunderstanding (possibly a typo) regarding TSpikes (rather, regarding the Badly Poisoned status). It starts at 1/16 max health and increments by 1/16 every turn. It might be worth discussing the situational use of 1 layer vs 2 layers, as badly poisoned Pokémon actually take less or equal cumulative damage for turns 1-3. If you're not fighting fat Pokémon, it is usually fine to only set up one layer.