He already gave a very good tech list, the other techs might be powerful but only second-rate to those must-have techs there. You can consult the skill FAQ to find techs that are 2nd or 3rd best to the best available to fill in the slots.
Oh, don't forget about the only Rookie tech worth keeping - Dokunemon's invisibility.
Considering the fact that you've pigeon-holed yourself with each digimon only having techs representing their type, you're not going to get 12 GOOD techs on each digi. In regards to Kongou (Baihumon's ability), Invincibility (Meteormon(Data)) and Invisibility (Dokunemon(Virus)) do the exact same thing but don't require 20 DP to get. As for Grisly Wing, it has one of the highest damage to MP ratios among all the attacks that hit every enemy digi.
1) For Vaccine type, Horn buster is much better than gigascissors claw, since it can't be used against bosses (as i know gigascissors claw and venom infusion always miss against bosses) and not 100% causing the opponent to miss
2) For Data type, add Sad Water Blast and Legendary Blade. Dealing huge damage to all enemy
3) For Virus type, add Puppet pummel and Evil Wind. Puppet pummel is the highest machine single target attack (very useful against darkness specialty digimon). Evil wind is often underestimated, by lowering enemy's speed it is very useful against high level digimon in tera domain, causing their chance to miss bigger and reducing your chance to miss
Speed does not affect their chance to miss. If you're capable of handling Tera Domain to floor 99, all your Digimon should be faster than the enemy anyway and you should wipe them clean before even getting to reduce their speed twice.
You CANNOT compare GigaScissorsClaw to Horn Buster. This is because Giga Scissorsclaw causes the enemy to have an increased chance to miss while Horn Buster just reduces tech power, it is two very different things. Post the final boss, you wouldn't be meeting any more bosses anyway.