Most Tanko profiles are focused on close-to-midrange firepower and a dangerous close combat threat. They are also designed to provide supporting long-range firepower for a link team moving up the board (Missile launcher and Flammenspeer). These threats give the Tanko's link a chance to move once or twice out of cover and threaten ARO pieces before the rest of the team moves closer in to their prime combat ranges.
This supporting firepower is more important in JSA than Ikari Co., but Tankos serve the same role in both.
Submachine guns make for good mid-range dueling and Suppressive Fire support in the reactive turn. Monofilament cc weapons and good CC skills keep enemy troops from moving too close. A Tanko won't be your star piece on the board, but it has the tools to protect your other pieces as they move in.
The missile launcher and submachine gun profiles are your primary defensive tools. The missile launcher can support a 5-man link as a tough-to-move ARO threat in a major fire lane; while the submachine gun can be advanced into the midfield and placed in Suppressive Fire to protect the rest of the link. While SF mode breaks the Tanko out of their link, heavy armor, 2 wounds, and the SF mode's modifiers will make it tough to shift from it's position. The rest of the link can then continue on in the next turn, or the link can re-form and advance further.
A Burst 2 contender is also something to be wary of, but shouldn't be the primary consideration of that profile.
Use the Tanko to provide defensive firepower for a link team, or provide long-range firepower as a team advances. After reaching the mid-field, consider breaking the Tanko out of a link (unless it's the Missile Launcher profile) and letting it loose with its impetuous order into the opponent's backline.
As with major link threats, a Tanko in a link is best dealt with by attacking weaker link members to thin out link buffs. Hacking is also useful (like with all non-specialist HI). A Tanko in ARO position will be difficult to shift, so taking it head-on is a bad idea.
When it's outside a link team, provide a model or two for it to 'chase' with its impetuous order into a dangerous firelane. Tanko's long-range weapons are disposable (aside from the ML), and can easily be neutralized from a distance given a solid ARO piece on your side.
Tankos should be primarily considered as part of a link team. They lack the consistent firepower needed to deliver themselves to their preferred range (the mid-field), and most of their skills are wasted as a solo piece.
If you decide to field a lone Tanko, consider using it as a board-edge distraction or support piece to draw attention away from your main threat.