Original 151 were the best.
Case 1: the starters.
The original Lizard Starters could eat any of the later on ones easily... :P
Case 2: Confusing order.
Apart from the confusion with Mew being after Mewtwo for reasons unknown, the order makes sense. However, we get devolutions of Pokemon in later on series', like Pichu, and that freakish looking Magmar prevolution...
Case 3: Jigglypuff is a Pokemon that only real men use... Or any Pokemon capable of Sing... You have to be tough to use it in a real battle...
Case 4: Without the originals, the new ones wouldn't exist. i.e. There can be no chimchar if there was no charmander...