Frozocrone
Miraculous!
I think Mimikyu being wild makes its odds of being weak much more likely since wild pokemon typically aren't very tough, especially at the start of a new saga. But if Pikachu loses to Mimikyu in SM004, I agree that it probably has more to do with Mimikyu being an opponent that Pikachu has had no experience with before rather than Pikachu himself lacking strength. ^^
I wouldn't mind it losing to Mimikyu, especially with it's Disguise ability. We also don't know the strength of Mimikyu (unlike the first battle Snivy) so we can suspend disbelief for a moment.