I'll just make some quick edits to the deck list then justify what's going on below. Make sense?
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3 Larvitar (MT)
3 Pupitar (MT)
3 Tyranitar (MT)
3 Chikorita (MT)
1 Bayleef (MT)
3 Meganium d (DF)
2 Mantine d (DF)
3 Stantler (SW)
2 Castaway
2 Buffer Piece
2 Warp Point
3 Professor Oak's Visit
3 Celio's Network
2 Night Maintenance
3 Rare Candy
3 Roseanne's Research
2 Copycat
4 Special Dark
2 Basic Dark
5 Fighting
3 Double Rainbow Energy
3 Scramble Energy
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First off, for clarification of what set pokemon to use, I've split up the evolution lines.
Pupitar's ability to spread damage AND it's non-existant retreat cost make actually having the thing active somewhat worthwhile. It's a mistake to overlook MT Pupitar in Tyranitar decks, as the big rock thing could make use of free pluspowers. The Tyranitar count is slightly lower, as you shouldn't need all 4.
You're playing the MT Chikorita and Bayleef, yes? (MT chikorita to avoid inconvenient snipe donks, MT Bayleef for evolution search)
There most certainly are good starters for this deck, and there most certainly are bad starters for the deck. Let's just fix up the basics a bit...
Mantine's a horrid start, thus the count for that is lowered to such a point that you'll rarely have both prized, but also rarely start with them.
Budew does very little for your deck beyond searching out Rare Candy. The low 40 HP makes it very dangerous to have active, and thus not too worthwhile in the deck. *Dropped*
Luvdisc isn't a half bad starter, except that you don't play stadiums of your own (to heal your pokemon). Therefore, I'm omitting Luvdisc in exchange for a starter whom will set more then just the basics up.
Stantler is being recommened in Luvdisc's place. The 70 HP is enough to avoid donks by any pokemon in the first turn (though a T2 Rare Candy can spell disaster for Stantler, like everything else in the game). Now, it's slightly better then Luvdisc in this build due to the fact that it searchs supporters out for nothing. This offers more support then just lasting through the first turn, and thus should prove more beneficial. There's no problem with reverting to Luvdisc should you feel uncomfortable with a pokemon whom can't "Call for Familly" if you will, but I personally prefer and would rather recommend cards that are not reliant on your opponent for their effects.
Now then, Trainers...
Bill's Maintenance does indeed shuffle a card back into your deck, but it does so before you draw. What if there was a card that still draws 3 cards, but shuffles a card back into your deck after you draw? Aaah, there is! Professor Oak's Visit from Secret Wonders! Just like Stantler, it's possible to obtain them from the SW theme decks (you get BOTH in the Electivire Theme deck, as well as another supporter I'm about to recommend), and thus should not be a problem implementing.
Everyone loves having Basic Pokemon. Everyone loves having Basic Energy. Sure, your old list might not have had problems getting basics out after Luvdisc got an Even Game off, but why wait for an attack? Why not have Stantler search for the fusion of Pokemon Fan Club AND Mr. Stone's Project? Give Roseanne's Research a try. It won't recover energy from the discard, but you already play Night Maintenance.
Copycat's a worthwhile supporter as well. It'll save you from Absol and Honchkrow trying to eat your hand up. It also is very evil to turn against Hurricane (when they aren't trying to do massive overkill with Energy Cyclone), Electivire decks, and most anything that runs Delcatty (PK).
Scott has limited use in this deck if Stantler's the starter. You're not running stadiums as is, so why play something that won't help you get anything out?
I also understand why you'd play Super Scoop Up, but I do feel it's uses here are not too great. For one thing, dropping Budew DOES make pulling that Super Scoop Up much more difficult. You also need to flip coins to use it, which is most frustrating. Knocking out Mantine'll become easier for your opponent, but keep in mind that doing so will set up Tyranitar's 1st attack, and as such is not that terrible. Loss of Meganium d's ability to reuse it's power might seem bad as well, until you realize that Meganium d only has 1 Bayleef to help it come out, and thus won't be using it's power that often anyways.
So. What in it's place? Well, we want even more energy (more then what just Roseanne's will give us). We want something to make Stantler not as crucial middle game, so we can start spreading with Pupitar. We want something to make sure Tyranitar or Meganium will last plenty of turns. We want Buffer Piece. And when you have tools, supporters, and energy, but lack a way to get it all out, there's little to place into your deck but Castaway.
So give these trainer and pokemon lines a try. The decreased numbers of some lines might feel a tad shaky, but the improved trainers should help. And don't forget that you can get plenty of the new supporters out of a starter deck (VERY important to keep in mind, rather then hunting on Ebay or in booster packs for the rest of your life)