In Version 1.2.0 and earlier, the game suffered from:
1.3.0 improvements:
While not perfect, the update made the game feel genuinely polished for the first time since launch. pokemon brilliant diamond 1.3.0 update
1. Union Room Overhaul (The Biggest Fix)
The most user-facing change: players can now link up with anyone via local or online without needing to be in the same “room code” session in a clunky menu. The update streamlined the Union Room interface, cutting lag when entering/exiting and fixing desyncs that plagued multiplayer battles and trades. For fans of the Underground’s secret bases, this also meant smoother co-op digging for spheres and fossils.
2. Pokémon Home Compatibility (The Real Headline)
While technically launched just before 1.3.0, this patch cemented full Pokémon HOME integration—allowing transfers from Legends: Arceus, Sword/Shield, and GO. Suddenly, the limited Sinnoh Pokédex expanded. You could finally bring in Hisuian forms (like Hisuian Growlithe and Zoroark) into Sinnoh, though they weren’t usable in the main story until post-game. This made competitive breeding and shiny hunting far more viable. In Version 1
3. Battle-Ready Fixes for VGC
Several moves and abilities got subtle backend tweaks:
4. Ramanas Park Adjustments
Slates for legendary encounters (Ho-Oh, Lugia, etc.) now have a slightly higher drop rate from digging in the Grand Underground. Also, a soft-lock was removed where leaving the park while a legendary was mid-battle could freeze the game. While not perfect, the update made the game
5. Minor Quality of Life
The "box swap" dupe glitch (using the Pokémon Storage System and moving at the exact frame of saving) was finally eradicated. Post-1.3.0, attempting the exploit causes the game to auto-save on exit from the PC, creating a rollback prevention.
Before 1.3.0, Brilliant Diamond was infamous for glitches. This patch fixed over 50 documented issues. Notably:
The update introduces a vast array of Pokémon native to other regions (Kanto, Johto, Hoenn, and Unova) into the Grand Underground.