And that's the whole argument for Wailord. It will take the opponent time to KO it, so they have plenty of time to build it. They can only look at the situation from that perspective because Wailord only brings one good thing to the table, it's HP. If it had any reasonable attacks, they could reason that Wailord could KO the opponent before it KOs Wailord, but because Wailord's only attack is awful, doing 60 damage for WWWC, and being that 60 damage doesn't KO many basics now, that reasoning would be flawed. People even suggest running DRE with Wailord to speed it up, which also shows how stupid the attack is if they are willing to reduce it's damage further down to 50 damage just to speed the slow whale up.
Here's the truth. Wailord only has HP going for it. It might heal a little damage here and there, but in the end, it's no tougher than 2 normal attackers. If it takes you 2 turns of attacking to KO 1 attacker, it should take you 4 turns of attacking (maybe even 3) to KO Wailord, regardless of what Wailord is doing/healing. If you can deal 80 damage a turn, you can three-hit-KO Wailord consistently and Wailord can't do squat about it other than spamming potions. If you have 130HP, it takes Wailord 3 attacks to KO your pokemon, because no wailord is going to sacrifice the space for a strength charm or plus power when they rely so heavily on leftovers and buffer pieces (and that stupid stadum).
Sure, Wailord might have a decent matchup against G&G and Magmortar, but will it ever get to the finals to actually face off against those decks? I don't think so. I don't think Wailord will win a single tournament until Battle Roads. I may be wrong, and if I am, that is fine, but Wailord just doesn't have enough going for it to really be championship material imho.