-I actually didn't notice that Shuckle could just learn Rest. That's a TM that you only get from beating the Orre Colosseum--and so far, I've only beat Lovrina and 1 other person in the next set.
-And I had Blissey not have Leftovers, because Mr. Mime doesn't have a healing move, and that goes well with Substitute, and Blissey already has softboiled.
-And I had Psychic on Blissey for coverage-sake, but I might go with Seismic Toss in the later-game (depending what works better in practice)--it's a real "toss"-up :D
-And I like Counter on him, because he has high defense to take the hit; but I might put something else there, now that you mention it.
-As for Meganium and Leech Seed--I'D LOVE TO HAVE LEECH SEED ON HER!--but it isn't available in Pokemon XD Gale of Darkness. You can only teach a Meganium Leech Seed through breeding, or trading one from G/S/C--and I don't have any trading device whatsoever--so I can't fulfill that (sad day). I really only put it there so that others can copy my team and use it for themselves.
-And while there are two leftovers in the game, I believe I can only use one variant of an item on a team for the Orre Colosseum--and any competitive battling.
-By the way, I'm surprised you didn't say anything about Delcatty. I looked at it just last night, and thought how stupid I was. The only thing that Delcatty had over my NEW choice was Attract. My substitute for Delcatty is Umbreon. Umbreon has insane DEF and Sp.DEF; also Umbreon can learn Confuse Ray--100% success; and Umbreon has a healing move, Moonlight, which is very good.
Anyway, when you have a chance, B&B, I made some changes, and let me know what you think. :)