Reinforced Suit is one of the best attachments in the game for Allies, period. It doesn't work for every deck all the time, but it is extremely flexible: It's not restrained to a keyword (like Avengers or Guardian), is playable on any Ally in play, extends the usability of any Ally, and is inexpensive.
Assuming an ATK or THW of 2, this is basically 4 damage or thwart for one cost, at the expense of time and the Ally slot. It offers flexibility as you can place it on the Ally that provides what you need at that time
Reinforced Suit enables mini-Voltrons builds for Allies that take consequential damage by enabling a couple more monster activations, e.g. Iron Man (Leadership) with Inspired,
I rate this card an A: Should be considered for inclusion in any deck with high-impact Allies.