(Moved from rules thread.)
Assuming that you want to make this team strong beyond the mere ability to roam the game without running out of PP, the main thing I'd suggest is that you avoid redundant move types. For instance, there's no need for Raichu to have both Thunder and T-Bolt. One will work just fine, which makes the other useless. (In that case, I'd drop Thunder and Rain Dance, as trying to set up a combo is dangerous when using a Pokemon with such low Defense.)
You can really increase your adaptability by dropping redundant moves and replacing them with some that cover weaknesses. The same idea goes for Venusaur (Frenzy Plant+Razor Leaf+Solarbeam), Arcanine (Overheat+Fire Blast), Gyarados (Surf, Hydro Pump, and Waterfall), and Hypno (Psychic+Confusion).
Your team also has a 3x weakness to Rock (super effective against Aerodactyl, Arcanine, and Gyarados). I suppose that Rock isn't the worst type against which to have a 3x weakness, but it's generally better to limit yourself to no worse than 2x weaknesses if possible. It's a problem if half your team can go down to one sweeper, and you'll wind up forcing Pokemon into matchups that aren't quite ideal just to avoid being susceptible later.
Still, for an in-game team with non-Surf HMs, it's not too bad. I can see how you might charge through the game this way. Just be aware that you could make improvements in order to bring this team to a competitive level.