I'm going to gague the wingless godflayer by the DMG guide alone. The guide does say that you can deviate from it, but that you'll get a "good approximation" for following it. So here's what you'd do if you followed the guide.
Upper_Krust said:
Wingless Godflayer Level 35 Solo Brute
Infant Gargouille
Titanic Immortal Aberration XP 200,000
Initiative +22 Senses ?
Initiative is correct, as far as I can tell. Senses should at the very least include Perception, which will be either +22. or +27, depending on if you train it or not. You might want to give it some other vision type too, of course.
Upper_Krust said:
Oddly enough, HP should be 1640
The official formula for solo monsters of ANY role is ((Level + 1) * 8) + Constitution
This is odd because Brutes normally get 10 + Con + (Level * 10), and elites take this value and multiply by two AND add an additional 2*Con, but... I dunno. This is what the DMG says. All the MM HP values go by this, at any rate.
Upper_Krust said:
Resist All 15
AC 51 Fortitude 37 Reflex 27 Will 27
Unless you're going by an entirely different system (I bet you are), Your defenses are a bit too low.
The way it's supposed to work is that the average defenses for any brute are level+12, modified up or down by ability scores. The modification isn't based on your absolute ability score, but rather it's "deviation from the average". The average ability score is 13+one half level, which in this case, is 30. Then you modify the defenses by deviation from that. (Note: the primary attack stat should be 3 higher, but that doesn't effect this formula)
So, Average defense is 47. Average ability for a level 35 monster is 30. Every 2 points above or below that should grant +1 or -1 to the defense. Solo monsters also get +2 to any three of the four defenses. So with your given stats, AC should be 47 or 49, Fort should be 52 or 54, Reflex should be 42 or 44, and Will should be 42 or 44.
Upper_Krust said:
Action Points 2
Speed 12 Swim 16
Oddly enough, speed guidelines aren't actually given at all in the DMG.
Upper_Krust said:

Virulent Bite (standard, at-will)
Reach 8; +39 vs. Reflex; 2d10+17 damage and ongoing 20 virulent poison (each save reduces by 5). Poisoned targets who reach 0 hp explode; Close burst 1; infecting those around them with an ongoing 10 virulent poison damage (each save reduces by 5).

Stomp (move, at-will)
Reach 12; +39 vs. Reflex; Burst 4; 2d10+17 damage and targets are prone (save ends) plus Follow-up "Squish" all targets still prone take 2d10+17 damage when the Wingless Godflayer moves again or makes another Stomp.

Tail Flail (immediate when injured, at-will)
Reach 16; +39 vs. Reflex; Blast 8; 2d10+17 damage and targets are stunned (save ends) and pushed 8 squares.
Damage... I'm not sure, as the chart tops out at 3d8+10 for medium damage, and 4d8+10 for high damage. The chart also makes little sense to me... usually, every fourth level gets another +1 to damage and every eighth level gets a dice increase, but sometimes this doesn't happen for whatever reason, and sometimes d8s increase to d10s, but more often d8s go to d6s. I guess 1d8 goes to 1d10, while 2d8 always goes to 3d6? It's weird.
Eyballing it, I'd say standard damage for level 35 should be (low) 2d6+12, (mid) 4d6+12, and (high) 5d6+12 (or maybe +11, for no apparent reason)
On the other hand, these standard damage values get modified in the MM monsters for reasons I'm not entirely clear on. The Tarrasque, after all, uses d12s!
Limited (as in, limited use ability) damage charts are also screwy, mostly going from d8s to d10s, but tossing in some d12s and d6s seemingly at random. The +x bonus increases or doesn't increase at random, again. Even so, I'd guess the level 35 continuation would be: (low) 5d8+11, (mid) 6d10+11, (high) 6d12+11
The attacks should be +38 vs AC, and +36 vs anything else... +36 and +34 (respectively) vs multiple targets.
As an additional note on stomp, I don't think you're allowed to do "Make prone (save ends)". If they were made prone and stunned (save ends), that would work for your purpose.
Upper_Krust said:
Infestation (when first bloodied, encounter)
20 Parasite Minions are freed from the Wingless Godflayer's crust.
Great Leap (standard, recharge

)
Reach 32; +39 vs. AC, Close Burst 16; 4d10+17 and targets are stunned (save ends).
Why just increase the reach? Shouldn't this be part of a move instead? There's lots of powers that involve moving, after all. Also, don't you mean recharge


? Or just

?
Upper_Krust said:

Feeding Tubes (standard, recharge

, immediate action if reduced to 0 hp provided ability is charged)
Reach 16; +39 vs. AC; All targets in reach; 2d6+17 damage and Wingless Godflayer heals 20 damage for each successful attack.

Frightful Presence (standard, encounter) *Fear
Close Burst 50; targets enemies; +29 vs. Will; the target is stunned until the end of the the Wingless Godflayer's next turn. Aftereffect: The target takes a -2 penalty to attack rolls (save ends).
Close burst 50? For a Level 30 Gargantuan Dragon (red), it's 10! I guess the increased range could be seen as offsetting the low attack, but still!
Upper_Krust said:
Collapse (when reduced to 0 hp, at-will)
All occupied squares; +39 vs. Reflex; 6d10+17 damage and targets are stunned and prone (save ends both)
Alignment Unaligned Languages Unknown
Skills Not sure yet
Str 44 (+39) Dex 20 (+27) Wis 20 (+27)
Con 40 (+37) Int 5 (+20) Cha 20 (+27)
No real comment at the moment.
Hope this helps. I realize that there's a GREAT amount of leeway from the guidelines, and they aren't NEARLY as comprehensive as you, but one still should probably be in this ballpark.