Just to let you know, I worked on the North American version, but now that I know what I'm looking for, I should be able to translate the cheats across to the EU version.
Summary of what's possible:
infinite special shot - Easy enough (already done in NA version)
tournament opponent modifier - Not happening
character modifier - Not happening
p1 auto win - I don't know what you mean by this
cpu auto win - As above
Since you don't get any way to upgrade the stats of players, there's no way to find where those stats are stored to change them. The player stats may not even be stored in ram at all. There's no way of knowing with the current cheat system.
Auto win? I can set it so you need to finish the current game? Or is it match? I dunno, I don't play tennis and never followed it. Either way, if you set the cheat it'll set your score to 2 / 2 and the current 'set' to 2 or 3 / 3 / 3 and the current set to 3. Just win the next round and you've won.
The same can be done for the CPU. Give me a few hours / a day to repeat the cheats for the EU version of the game.
Oh and I spent hours trying to find the current score (ie 30 / 15 or whatever) and could not figure it out. Frustrating.
Edit: See attached.
Note the number of Sets location moves around a bit. I've included it in the cheats, but it may not always work. Not much can be done about that. I've also set it that you effectively cannot lose. Activate the cheat and the button combo and you'll end up with a set score high enough that you can't lose irrespective of whether you do win the each game or not. Sadly, because of the shifting Set count, you might have to play each set at least one (you could just lose, I guess, and still win).
The CPU cheat works the same way, making it impossible for you to win. Dunno why you'd want that.
If you have any issues let me know.