I just compiled all of the sprites. Here's a list of what still needs a shiny backsprite:

098/Slowpriest
106/Abyssus
108/Tellure
112/Gargoth
113/Cragoyle
121/Drakodo
128/Chloreon
129/Chiarame
130/Serberine
132/Engil
133/Benengil
134/Duval
135/Malduval
139/Brontogon
140/Blitzfaust
141/Vilephist
145/Sinestril
146/Malistril
149/Bakurge
151/Sirene
152/Iglonia
154/Caribrisk
155/Huskii
156/Tundrolf
157/Wolfrost
158/Reefrain
159/Polara
160/Polarice
162/Ferrian
165/Cackinge
166/Scorchion
176/Misticade
177/Kraklaw
178/Leoracle
179/Khaphix
180/Flintusk
181/Metusk
182/Allufang
183/Kunaiga
184/Purior
190/Snarliger
191/Noctiger
192/Raiger
193/Gypseer
194/Tagati
195/Neichia
197/Typhidna
198/Unicrown

Pretty sure I got everything, but if i missed something, lemme know so I can add it to the folder.

EDIT: Are we making new sprites for the old Pokemon? I don't have any of those.