Yes, I have seen that in my Pokémon Guide. Some Pokémon is there, said to be in the game, but the guide says their not available and their is no information (stats and such) about them.
By the way, I have heard you cannot trade between the japanese and american version of the games so I tested to be sure. I had a jp silver and an us gold and I was let into the trading room! But when I was about to trade a text said in the us version: 'Your friend's ??????? seems to be abnormal. Sorry, but the trade is canceled.'
Ok, I thought. You cannot trade. So I was about to cancel, but when the arrow you choose Pokémon or cancel with did not work (in the us verison) as it should have. Instead of the arrow appear before the 'C' in Cancel, it appeared in place of the 'e'. I pushed the A button an data on this Pokémon appeared:
(a Mewtwo sprite) No.150 L.253
/Mewtwo
(a HP meter that is half and yellow)
A21/A21
Status:Pokérus
Exp. 213954
Level up 6269876
To 254
(the exp meter is full)
Item: Star piece (don't know what that is)
Sky Attack PP:0/5
Transform PP:0/40
Petal Dance PP:0/20
Petal Dance PP:61/32
IDno. 20640
OT/?
(And each of its stats is A21)
I was named Satoshi in both verisons, but the jp said the friend was suriiputekumo (sleeptecmo maybe) and the us said the friend was KTL. In the US you could not see the friend's pkmn, but in the japanese the friend had (which I did no thave):
No.006 Teatosoteku/Rizaadon(Charizard in the US) Lv.0
HP: 0/(some strange symbol)48
Exp. 5111808
665354
Lv.1 (full exp meter)
Reitoupanchi PP:13/21
Atk:0
Def:(a strange symbol)44
SPCL. Atk:(other strange symbol)96
SPCL. Def:(other strange symbol)96
SP:(strange symbol)44
There was also a Zubat (which I had) but this one was strange.
Also 3 ??????. One had the attack Hasamu PP16/30, the other had Tsubasadeutsu (wing attack) PP16/35, the third Kaminaripanchi PP:7/24
At the US version, in the empty list od friend's pkmn you could find these:
Lv.153
78/Nidorino
HP: (full meter)-52/ö37
Status: BRN Item: Charcoal
(its techniques:)Spore, Poison Gas, Petal Dance, Petal Dance
Atk:149
Def:;79
SPCL. Atk:I01
SPCL. Def:ä60
SP:ö23
No.00 L.0
777777777777777777777777777777778
(The info about this pkmn changes from)
Status: FNT
Type: Steel
(to)
Status: Steel
(and then to strange symbols)
Again in the jp verison:
/Yadoran
(no attack here) PP:10/67
Haganenotsubasa (metal wing) PP:63/28
Daatarukoudoru PP:48/24
US version: (a sprite of Hanekko/Hopip, which I have at the jp verison) L.0
77777777777777777777777777777/Hoppip
HP: (full meter) 60/60
Status:PSN
Item:SlowPokeTail
Confusion PP:0/25
OT/;J
Atk:60
Def:28
SPCL. Atk:0
SPCL. Def:0
SP:60
There was also a strange Haunter, Lv.0 with a SlowpokeTail and OT/mj
It's a very strange and funny glitch when you try to trade betwen two non-compatible games. I wanted to see what happened if you started a Pokémon battle:
US version: you encounter ! (a mewtwo sprite)
JP version: you encounter (a sprite of Sakaki) He sends out an Arboc.
The next time I tried, Sakaki in the US version send out himself, called '!'
Unfortunatley the game froze before the battle started.
So, this is what happens if you try to trade/battle bewteen the US and JP versions of the games. No effects on the games afterwards though that I have seen.