is your intention to boost for tournaments or for the arena? If your boosts are limited I would probably hold back on booting any of these minus Tarbog. Dio isn’t really worth boosting for the long-term game. Tarbog will be good for toruneys no matter what so that you can boost without feeling like you are losing out any.
Indog 2 is also good to boost for tourneys and raids as well - just be careful not to boost speed too fast for raids. Max recommendation for most raids is 136 speed. If I were to boost Indog 2 myself I would probably go for 136 speed, then a split on hp and dmg (IDK how others boost, so if anyone has better suggestions let me know). If you don’t plan on using IndoG2 for raids, then speed is your friend in tourneys - I’d say probably 145-150 is fairly common when people want a speedy IndoG2, and then the rest split between dmg and HP.
Tarbog is typically 0/20/10 by most of the pros, so that would be the build I would aim for myself.
Dio, I would not boost - no reason to. It’s fine base for raids, and it will not hold up long in the arenas. If you do want it boosted just for fun, and I would stick to a good split between dmg and HP (maybe 15/15/0 or your 17/13/0 is also good). Though, I have run into some speedier dios and they did ok, it just will mess with raids to some degree.
Spinocon, I can’t remember how people used to build it - I was never into the snake and now it’s being phased out of most teams due to power creep, but I would think you are on the right track with more HP, less dmg, and some speed. Some Dmg might be nice for when you encounter some creatures with bleed immunity, I’d have to ask my friend who is obsessed with the snakes what his boost spread is lol. For long term, though, spinocon might not be the best choice for boosting, unless you hope to use it in tourneys, in which case it does ok.
Indot - HP is a must. I am working on a 13/6/10. Some people add a bit more speed (128 is fairly common), and some a bit more hp (14 boosts), but this seems to be a fairly typical build. You need the HP to survive hits, and IndoT already has enough dmg output without boosts, the main focus should be hp and a bit of speed.
Dracoceratops is ok for tourneys, but it, too has fallen out of due to power creep, and there are a lot of different builds out there should you choose to boost it. The most common boosts on dmg and speed with just a little hp. But then I’ve seen just about everything lol. If I were to build one personally, I’d probably go for about 130 speed or a little faster (136), and then a good chunk in damage and then some hp, but that is just me. I’m sure there are others here who have better suggestions, however, so I’d wait on them to hear what they would have to say.
I wouldn’t boost spinonyx. But that’s just me. It might be ok for some tourneys but overall it’s got too many counters and is fairly weak for what it is. Some people might disagree, though, and so I would just go with what makes you happy 
Ankymoloch is great for tourneys, but other than that it’s just ok. If I were to boost for tourneys I would go 17-20/10-13/0. Or just split the boosts evenly between dmg and hp. Really no reason to speed because it has decel and instant moves.
Again, these are just my personal preferences. There are others here who probably have great advice as well, and I would go with what you feel is best for you. In the end, everyone has a slightly different style of play, so I would go with what makes you happy 
