Who to spend Fast TMs on?
I currently have 550k stardust, 6 Fast TMs, 3 Charged TMs, 62 Rare Candies and a full bag that needs as many Great/Ultra Balls (plus berries) as possible to farm double stardust. Once the Entei raids are over, I may struggle to earn more TMs, so I should not spend too many (especially with Gen 3 coming soon).
Current attacker squad comprises (all L30 wonders) DT/OR Dragonite, MS/SE Rhydon, RT/SE Golem, Count/DP Machamp, RS/DP Poliwrath, WG/HP Vaporeon, Bite/HP Gyarados and Conf/Solar Exeggutor. Could power up another four wonders: L28 Conf/FS Espeon, L20 TS/WC Raikou, L23 Conf/SB Alakazam (requires 3 more candy) and L20 Larvitar (145 candy + 45 Rare, may need a TM or two).
Candidate 1: Dragonite
My other three wonders are L30 with SW/DP, L22 with SW/Hurr and L20 with SW/HB. Hard to argue against adding a second Dragonite to my core team, but hard to decide which. Although I would save stardust, the legacy DP is worse than OR (already have) and Hurricane (for soloing easier T3 raids, notably Machamp, and attacking Blissey/Chansey/Snorlax).
Candidate 2: Lapras
I have a L30 with WG/IB (caught attention) and a L28 with FB/IB (above average). Back then, I used the former as a defender and the latter for prestiging Dragonites. The former could play both roles better with a Fast TM (and no need to spend stardust). Doubt I will ever catch a wonder Lapras in the wild and any from eggs or raids would be L20 (not worth spending 75k stardust on).
Candidate 3: Gyarados
Since I only use my L30 wonder with Bite/HP as a slightly worse Vaporeon on attack, I might as well make him more useful as a defender, just like he was in the old system. May regret this if Psychic-type raid bosses become more relevant or Gyarados is given Waterfall as a possible quick move.
Candidate 4: Donphan
Just hatched and evolved my first wonder, with Tack/EQ, and was advised to use a Fast TM to get Count/EQ. Is he really worth spending 75k stardust on? Is he likely to get a Ground-type quick move when Gen 3 is released?
Candidate 5: a) Arcanine b) Entei c) Flareon
The current metagame is not kind to Fire-types, but they remain vital for soloing Scyther (will try once Entei is gone) and attacking Blisseys with DG (which destroys Dragonite, Machamp and Tyranitar). My L27 Arcanine with Bite/FT (or evolving a L30 wonder Growlithe) would cost the least stardust, but my 15A/15D/11S Entei (five more days to try catching a better one, also need to spend Rare Candy) or Flareons with Ember would be more powerful.
Answers
6 FTM 3 CTM is not much so you do not need to spend any if you don't have a pressing need for something in particular. I would try to save a bunch in case a moveset change with gen 3 shakes things up.
1: Best candidate. If your Machamp solo team needs a boost, it's hard to go wrong with Hurricane Dragonite. Note that OR is better in every matchup where Hurricane is not super effective.
2. Not useful enough. The L30 would be such a minor increase over the L28 that it's not worth a TM at the moment.
3. Wait and see if it gets a water-type fast move. It's not such a stellar defender either way, bad reason to spend TM.
4. If you really really need a ground attacker, Donphan is decent. I would personally not spend dust on him since better ground mons like Rhydon and Golem exist.
5. Arcanine is worse than Flareon. Entei is worth TMing if you decide to power it up. Flareon is ok for killing Blisseys but I'd rather evolve new Eevees than spend TMs. If that sounds like a hassle, maybe FTM a Flareon that already has Overheat, but only if you really need it. Machamp and Dragonite are better at killing Blisseys even with DG.