Currently I'm working on a straddle strategy.

It's based on Bollinger bands narrowing and triangle (flags) charting.

Is there a formula that covers any of these prerrequisites? Thanks in advance. 

It is easier to identify narrowing Bollinger Bands in TC2000 v12 or v16 than in TC2000 v7. You can add a Bollinger Bandwidth indicator to the chart and then click on it to select Create Scan Condition.

Create Conditions from Your Chart (5:25)

Useful conditions for this would be Moving Down, Less Than and New Low.

You can create Personal Criteria Formulas based on Bollinger Bands which can be used in TC2000 v7 however. The Finding Expanding or Contracting Bollinger Bands explores one way to find contracting Bollinger Bands. Searching the forums for Bollinger Band Squeeze also returns a number of results with varying interpretations (the following list is not comprehensive).

bollinger band squeeze
Bollinger Band Squeeze Scan
bollinger bands
Modelling Bollinger Bands (& Standard Deviation) in a TC PCF

You may wish to review the following for information on pattern recognition in TC2000 (focusing on topics mentioning flags, wedges and pennants).

Falling wedge
Cup with a handle formation
PCF for cup with a handle
Scanning for Chart Patterns
Scanning for Stocks Printing a Double or Triple Bottom
PCFs for pennants and flags
PCF's for Triangles
Does TeleChart support Elliott Wave indicators?
Double top/bottom trend
Finding Double Tops and Double Bottoms
CUP AND HANDLE AGAIN
Finding Continuation Triangles And Wedges With Telechart
Cup & Handle PCF
Double tops and bottoms
Flag wedge and pennant pcf
05/01/2012 Webinar: Trading the Flag and Pennant Patterns
Head and shoulders
TC 2000 Bull flags, Bear Flags
PCF for rounded bottom trading

That said, I personally do not think complex pattern recognition is practical in TC2000 using formulas and Scans.

They are at the very least beyond my abilities to help you create without a specific unambiguous objective definition of what you are attempting to identify. It can't be an I know it when I see it type of definition or be based entirely on an image.

This is true of pattern recognition in general with the exception of fixed size candlestick patterns, which are fairly straightforward as long as the pattern is well defined. The first topic referenced in the post has formulas for candlestick patterns.

The following topic has has Condition Formulas to identify candlestick patterns in TC2000.

Boolean PCFs for Candlestick Patterns

Thanks for the information and the supplied material, regards

You're welcome.