I think I get what you're trying to say...
I made a post or two about a tentative dragon egg group team, for a battle frontier match.. which would include the ones you mentioned.. sans Feraligatr since it actually isn't in the dragon egggroup (it is in the Monstergroup, along with the other ones mentioned)
I don't think that it's a pattern, but I think that since most of them are speedy, that it's no coincidence that they're on Ash's team. It's also because they're kinda popular, especially Charizard was, so I think the animewriters want to build a team in the same mold.. which might be a reason why we see so many turtles/lizards on Ash's team.
About Gible being of the Dragontype, being an Uber and all that kind of trashtalk.. There's nothing really to back that up after yesterdays episode.. as Gible.. the mighty dragon/uber got stomped by Empoleon.. (yes I know of the un-trained situation vs. trained since day 1 and the bad type match up..) That shows that a Gible can be beaten in a regular match (I'm not counting the Gabite vs Pachirisu debacle since that was a contest match)