Learn English – When to use the verb “discuss” vs when to use the abstract noun “discussion”

The important thing to note about your "special abstract nouns" is that they are all derived from verbs:

attempt .. from attempt, verb
decision ... from decide, verb
order ... from order, verb
* tendency ... from tend, verb

Once you recognize that, the function of the following infinitival clauses becomes clear. These verbs all take infinitival complements:

They attempted to go.
She decided to make a cake.
He ordered the regiment to retreat.
We tend to use these weapons when we are threatened.

The infinitivals have exactly the same function with the derived nouns: they act as complements, expressing what is attempted, decided, ordered, or tended.

Strongest would be an abstract noun if the sentence was written like this:

Elephant is the strongest.

You can't have two nouns back-to-back without a conjunction such as and or or.

The pattern is almost always this:

{ Article / determiner } { Adjective } { 2nd adjective, etc. } .... { Noun }