Upgraded fairies are better than any ravens at the start, and Grindan + Mass Slow on the second week will take any stronghold without casualties! So, let's argue about the Garrison. And the weaker players on upgraded fairies will run away and gather more resources.
P.S. I know that upgrading fairies is forbidden, but if it were allowed, it would be a huge advantage!
Added 7 minutes ago
It will be very difficult to take the maximum - because even with a fortress upgrade from 1-7 + fairy upgrade on the first day = 4 Phoenixes, 4 Psychics, 10 Fire Elementals, 8 Earth Elementals, about 20 Air Elementals, and under 80 upgraded fairies, losses are inevitable - and in the case of Griffin morale and an attack on the fairies = a complete defeat.
Grindan's combat parameters will be weak... approximately 2-1-7-6
In the spellbook, Mass Slow and Bless, and Mass Stone Skin.
Phoenixes may lose one unit in the first attack, without killing half of the stack... fairies and psychics will attack without response - but with difficulty and most likely, together with the Air Elementals, they will finish off the stack of upgraded fairies - and then the gradual encirclement of the Elementalist's troops will not allow avoiding melee combat, in which neither the Phoenix nor other troops are suitable for retaliating, and only fairies and psychics will attack without response, and this is despite the fact that Griffins attack 2 times ;) , and still there will be at least 6-7 rounds... how many times do Griffins usually get morale in this case? ... I think at least 3 times - and here is the result...
P.S. Of course, if there are additional troops to the native ones, it will be easier - but only with native troops, if you take them, then either a couple of birds + some of the Elementals, or a large part of the monsters of ranks 2-5 will be defeated. (this is without Griffin morale, max 1, which is not critical)
In contrast, I will say that an Elf, taking into account the current rules (without fairy upgrade :)), takes the maximum with native troops on the second week without a rank 7 unit, which is more realistic.
And, in fact, Valeska has good chances - but the problem is having Mass Slow at the beginning of the second week, and the first turn (a single King Griffin or cavalry that has been in the stables).