After 3 years this is a pretty ridiculous bump, but this is the only thread I could find on E4 about serial code variants. Thanks to a recent post by @lucid , these serial numbers have been bought to my attention. I had absolutely no idea there were differences, but I’ve already found one Pichu card which has 2 variants which isn’t mentioned in this thread:
| Card | Variant 1 | Variant 2 | Variant 3 |
| ● Pichu - EX Emerald (59/106) - EX Emerald stamp | BSW-3XN-WTR | - | - |
| ● Pichu - EX Emerald (59/106) | - | BSW-3XN-JCR | BSW-3XN-CUU |
| ● Pichu - EX Emerald (59/106) - Nintendo World stamp | - | BSW-3XN-JCR | - |
It’s interesting here that the card with the EX Emerald stamp has a different serial number to the regular card. In the EX Holon Phantoms and EX Power Keepers sets, both the stamped and unstamped cards have the same serial number.
Excluding the above EX Emerald cards, this is what I’ve identified so far from English sets:
| Card | Serial Code |
| ★ Pichu - EX Sandstorm (20/100) | M2G-B0E-1HC |
| ★ Pichu - EX Sandstorm (20/100) - Reverse | M2G-B0E-1HC |
| ● Pichu Bros - POP Series 3 (16/17) | RV7-5UH-W7B |
| ● Pichu - EX Holon Phantoms (76/110) | 0AC-3AY-0U3 |
| ● Pichu - EX Holon Phantoms (76/110) - EX Holon Phantoms stamp | 0AC-3AY-0U3 |
| ★ Pichu - EX Power Keepers (21/108) | Q3V-H00-N8F |
| ★ Pichu - EX Power Keepers (21/108) - EX Power Keepers stamp | Q3V-H00-N8F |
I can’t find any variations on any of these cards from my own collection (I have quite a few duplicates) nor from Googling the cards and looking at various images. I’m really keen to know if any other variants exist. The variants from the EX Emerald set are very obvious, with about 50% of the cards I looked at having different serial numbers. Despite being common, I can’t find any variants from the EX Holon Phantoms set at all.