Croconaw's essentially god once you arrive at Ecruteak anyway thanks to roflsurf and you get ice punch from the previous city. Gyarados can't compare with Feraligatr, but I don't see how Feraligatr's awesomeness at Chuck and co. force Gyarados down: if Gyarados doesn't have as much of a problem beating them as Feraligatr, then I don't see why it should be sandbagged as a result.
Also Outrage hits Gyarados's stronger defense from Dragonite's weaker offense, it's 90 power, and Icy Wind happens to slow Dragonite down so Gyara can KO. Lance's Gyarados is pretty easy to counter: as his lead, all you need to do is to lead off with an electric-type or *insert derp here with Thunderpunch*, OHKO, and take care of the rest. RD Gyara isn't much of an issue imo, and neither is Thunder.