If it's not waking up and your risking it getting taken out not knowing if you'll need it later, you have to switch it out.
Lets say Ash did do the "smart thing" and switch out Dragonite... It would still be asleep later on wouldn't it? We've seen these Champions send out their aces earlier than expected (EX: Steven) - What's stopping Cynthia from simply sending out her Garchomp in return and just instantly taking out Ash's Dragonite when he does ultimately decide to switch it back in? I feel like people really are treating him not recalling a sleeping Pokemon like the worst mistake in history at this point...
Heck, she could even send in Togekiss who is part fairy, and who if the writers deem it, could possibly have a fairy type attack.
If he picks the match up correctly, Dragonite shouldn't get unnecessarily knocked out. At least not in sleep. Roserade/Gastrodon would have been good opportunities had Ash planned like that.
Again, Garchomp/Togekiss exists... I feel like it would still get knocked out, we saw how long it was asleep to the point of Spiritomb being able to use multiple Dream Eaters, I feel like that would give Cynthia plenty of time to use at least some time to call in an easy counter.
That's actually what can happen in the game, sleep isn't freeze. It's a mechanic with a set number of turns in which the earliest it can wake up is immediately. The latest being 3 turns, meaning Dragonite likely would have woken up if Ash had returned it after the 2nd Dream Eater, when it came back out.
This could have been a good strategy I'll give you that... But when it comes to using game logic in regards to the anime which seems to defy game logic whenever the writers see fit, I'm not sure.
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Anyway - Overall it's fine to criticize since it would be boring if everyone was just hyped about everything, but I really do feel like there are some people on here who have the most extreme reactions, and that's where I find posts to be exhausting to read IMO. (Also talking about the recent leak when I say this - people having extreme reactions to an episode that hasn't even come out yet to even properly judge decisions and what not...)