Couldn't pick one for each generation so here's five for each:
Gen 1: Lapras, Vaporeon, Pinsir, Charizard, Weezing
Gen 2: Noctowl, Ariados, Typhlosion, Quagsire, Houndoom
Gen 3: Crawdaunt, Walrein, Exploud, Kyogre, Sceptile
Gen 4: Torterra, Lopunny, Drifblim, Luxray, Roserade
Gen 5: Samurott...