Well, I guess I´ll help you. I warn you, I´m not an expert on this by far, but from my experiences playing through the game this is what I have to say:
Snivy- Well, you already selected your starter, and that makes it all easier. Serperior´s highest stat is speed, and it has nice defenses too. Serperior´s main problem is that it has severe moveset issues. (But I guess that´s true of all starters.) You´re pretty much learning only Grass moves and a few Normal moves by level up, so try to get a TM like Dragon Tail or Aerial Ace on there.
Strong/Bulky/Fast is kind of the same as asking for "a good team", but I´ll try to match that description anyway.
Serperior´s got the "Fast" part down, but I don´t consider it very "bulky". Time to get that part down.
Alomomola- With it´s phenomenal HP, Regenerator, and interesting moveset, your opponent will never take this down. It´s moveset is so much better that Seismitoad´s, too. Alomomola is more physical-defence based.
-or-
Jellicent- Again, awesome HP, awesome abilities, and a moveset that puts Seismitoad in shame. However, unlike Alomomola, it can actually fight back. It is more special-defense based.
´Kay, the team is now reaching two members. I think it´s time to focus on speed again.
Volcarona- This popped into your mind, didn´t it? It´s crazy fast and special-oriented. It has a moveset that delivers, too. Fiery Dance is a must. Unfortunately, it requires trading to attain at a reasonable point in the game. Not that that´s a huge issue, however.
Three members! Woot! Halfway there! If you like the Hit-and-Run technique, maybe consider:
Zoroark- It has awesome attack and speed, which means it can take out anything before it has a chance to hit Zory, which is essential considering it´s defenses. It has U-turn, which makes it worth considering as a lead when you don´t know what you´re facing. Besides, it´s unique. It requires some trading, though.
´Kay, at this point you can afford to have slower Pokemon. Why not consider:
Reinclus- Believe me when I say that I wanted to suggest Gothorita more, but Reinclus fits the team better. He´s a special powerhouse and his HP is promising. Surprising, however, is his shallow levelup moveset. Like Serperior, he needs TMs to help him out and give him variety.
Stunfisk- It´s not as bad as everybody thinks. If you stick a Quick Claw on it and forgive it´s pitiful Speed and Defense, it will reward you with nice HP and Special Attack. Again, it´s unique and not common, so that´s another special thing about it. It has a decently varied level-up moveset
starting a level 40 or so, but before that you´re forced to use TMs to get the job done.
There you have it! I hope it helped you consider at least one member for your team.