Accordingly, Isaac will be permanently trapped in the boss room of Mausoleum II if he succeeds in opening the door in Depths through an alternative method.
Even if he escapes the boss room, the game will not progress, and he will be stuck on the floor forever.
TMTRAINER will not affect Knife Piece 2 due to the game suppressing TMTRAINER's effect. However, it will affect Knife Piece 1; as such, Knife Piece 1 must be picked up before obtaining TMTRAINER to gain access to the Corpse.
TMTRAINER will affect both Key Pieces dropped by Angels, preventing Isaac from opening the door to Mega Satan this way.
Items affected by TMTRAINER may take the effect of rerolling all of your items. This includes TMTRAINER itself, meaning any future items you encounter will not be under its effect, nor will the items obtained by rerolling due to the glitched item.
If an item held by Isaac is rerolled into TMTRAINER (Either by D4 or a 1-pip Dice Room), all items after it will be rerolled into glitched items.
If crashes are commonly encountered in the DELETE THIS challenge, TMTRAINER has the same effect and may be unstable.
'M: Rerolls glitched actives into other glitched actives.
Bag of Crafting: Recipes are not glitched. Can craft TMTRAINER but will have no effect.
Binge Eater: Functions as intended, cycling pedestals between a glitched item and an HP up item.
The name and description of the item comes from the result of glitches in Pokémon Red and Blue. Certain glitch moves in that game can have names so long they run into the memory, corrupting it and causing glitchy effects, like the opponent's name becoming "TMTRAINER". A certain other glitch (commonly referred to as the ZZAZZ glitch) replaces the letters in the player's name with capital Zs except for every third letter.
The pickup quote for this item is defined as "Isaac and his mother lived alone in a small house on a hill", but in game it's shown with the pattern of Zs overlaid on top.
The sprite is a reference to how sprites corrupt in Pokémon Red and Blue, especially after encountering glitch Pokémon.
The effect of the item is similar to a "Randomizer" for other games.
The music fading out and status effects being applied to enemies upon acquiring the item is a direct reference to the effects of TMTRAINER in Pokémon Red and Blue, which fades the music out upon use until another song is triggered to play (assuming the game survives the effects), as well as applying burn and frozen statuses to enemy pokémon.
The item's effect is a reference to an old randomizer mod that came out before Afterbirth+.
The sprite for TMTRAINER itself is a heavily glitched version of Isaac's face, affected similarly to the face of Tainted Eden in menus.
DELETE THIS will always be unlocked before TMTRAINER on any given file. This item, The Small Rock, Dirty Mind, and Spirit Sword are the only items that appear in challenges before they are unlocked. Small Rock and TMTRAINER are also notable for not being unlocked by beating the challenge they appear in.