Um, are you retarded? lol not to be mean, but the only thing Talonflame outclasses Charizard in is speed, and that's about it. Charizard has better attack and defense stats, and still has decent speed, Talonflame still falls short, it has the shittiest movepool, and is only good for taking out things it's strong against, Charizard has greater coverage, and is overall much better than Talonflame lol
Tyranitar is stronger and more useful than Blastoise, both as a beast attacker or a great special wall (Sandstorm skyrockets its special def) he is more than good enough to compensate for its weaknesses
as for Serperior; Behind Blaziken and Greninja, it just might be the strongest starter yes, after that probably comes Venusaur
Never really used a sandstorm set, so I wasn't particularly aware of the sandstorm effects, but still, Tyranitar is pretty slow. I wasn't really a fan of greninja tbh, he was KO'd quite a lot during my play through, and left a sour taste in my mouth.