Hueg list of glitches, some fun, some dangerous:
DANGEROUS
- Putting your DS to sleep mode after quitting a Battle Video and while the Battle Recorder is still shutting down.
- Putting your DS to sleep mode while fighting with Suicune.
The two glitches will make your save data show a black screen upon loading.
The only way to fix it is to bring it to a Nintendo Support Centre.
Dangerous
-
Using Pursuit on a switching Pokemon while there is a weather effect active. Same glitch as Platinum, will make your current battle very buggy,
- Checking your partners Pokemon in Multi-Battle at the Battle Tower, and pressing "B" while the message, 「つよさをみる」 is showing. It'll freeze the game.
- In the area with Articuno, there is a ladder on its right. DO NOT climb it from the back, or you'll be stuck in a black area of nothingness. Climb it from the front to avoid this bug.
Kinda annoying, nothing too bad
- HGSS has environment sounds, and sometimes they get locked. This happens when you Fly to an area with the same BGM while in range of an object that generates environment sound.
- Touch screen gets locked when talking to Oak at Pallet. Only happens when you try to move while his message window is showing.
- Slowpoke Well Strength bug, as mentioned earlier.
- In the Unown Note, "!" gets registered even if you capture "?" first. "?" gets registered is you capture a "!" afterwards.
- Some pixels missing. See the moonspeak wiki if you are interested, there are a few.
- Daycare Woman tells you the same info twice, if only one of two Pokemon at the daycare has leveled up.
- After contracting Pokerus for the first time, your lead Pokemon being dead, and going to the Pokemon Centre: For some reason, your second Pokemon will be following you, but it'll be treated as your lead Pokemon. Bug will be gone after switching screens.
Typos
- Text for Gooey Mulch and Damp Mulch switched in the instore explanation. Not much of an issue for non-Japanese readers though.
- The younger Haircut brothers's price is shown as 400 yen ingame, but only 300 yen is deducted (300 yen should be the right price, however.)
Info ripped from HGSS wiki.