The Hyper Beam automatic selection glitch is a glitch in Pokémon Red, Blue, Yellow involving a Pokémon using Hyper Beam two or more times in a row (without it recharging), after a faster enemy Pokémon uses a partial trapping move (Bind, Clamp, Fire Spin or Wrap) during the recharge turn and misses.
This glitch allows the player to underflow the current PP of Hyper Beam to 63 with three PP Ups applied, or remove a PP Up effect.
This glitch or the switch PP underflow glitch can be used to get a 'FF' PP value for the Generation I max stat trick.
It may take a while to successfully pull off this glitch to get 63 PP outside of a link battle due to the luck involved with having the right Pokémon appear, having Hyper Beam hit, and having the opponent choose the partial trapping move and miss. It may also be tricky to keep the prevent the user's Pokémon from fainting.
Suggested set up
- User: A low level Chansey (low enough to be slower than the opponent) with Double Team with 1 PP, and Hyper Beam. Chansey was chosen because of its high HP.
- Opponent: A level 15 Tentacool with Wrap (can be found in the water south of Pallet Town).
1. Have a slower Pokémon use Double Team six times (recommended).
2. Have the faster Pokémon use any move that won't faint the opponent.
3. Have the user's Pokémon use Hyper Beam and have it hit.
4. Have the opponent use Bind, Clamp, Fire Spin or Wrap and miss.
5. The user's Pokémon will use Hyper Beam again automatically without having to recharge.
(6.) If immediately after this glitch the faster Pokémon uses a partial trapping move and misses again, then Hyper Beam will be performed without having to recharge again. This can be repeated until the enemy Pokémon faints.
PP underflow explanation
If the PP was 0 with no PP Ups applied, it will underflow to 63 with full PP Ups applied. If it was 0 with at least one PP Up applied, it will underflow to 63 with one less PP Up applied.
This is because in Pokémon Red, Blue, Yellow and Pokémon Gold, Silver and Pokémon Crystal, PP and the amount of PP Ups applied are stored in the same byte. If bit 6 (+40h) is set, then it indicates that one PP Up has been used. If bit 7 (+80h) is set, then it indicates that two PP Ups have been used. If bit 6 and 7 (+C0h) are set, then it indicates that 3 (the maximum amount of) PP Ups have been applied.
Examples: A value of 40h means 0 PP with 1 PP Up applied, a value of 80h means 0 PP with 2 PP Ups applied, and a value of C0h means 0 PP with 3 PP Ups applied. A value of 3Fh means 63 PP with 0 PP Ups applied.
There are only 64 (80h-40h) possible values for PP itself, meaning that the maximum amount of PP is 63.